U.S. patent application number 12/750539 was filed with the patent office on 2011-04-07 for novel dyes and use thereof in imaging members and methods.
This patent application is currently assigned to Zink Imaging, Inc.. Invention is credited to Kap-Soo Cheon, Michael P. Filosa, John M. Hardin, Fariza B. Hasan, John L. Marshall, David A. Skyler, Stephen J. Telfer.
Application Number | 20110080458 12/750539 |
Document ID | / |
Family ID | 40913229 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110080458 |
Kind Code |
A1 |
Cheon; Kap-Soo ; et
al. |
April 7, 2011 |
NOVEL DYES AND USE THEREOF IN IMAGING MEMBERS AND METHODS
Abstract
There are described novel rhodamine dye compounds and imaging
members and imaging methods, including thermal imaging members and
imaging methods, utilizing the compounds. The dye compounds exhibit
a first color when in the crystalline form and a second color,
different from the first color, when in the liquid, amorphous
form.
Inventors: |
Cheon; Kap-Soo; (Shrewsbury,
MA) ; Telfer; Stephen J.; (Arlington, MA) ;
Filosa; Michael P.; (Medfield, MA) ; Marshall; John
L.; (Lexington, MA) ; Hasan; Fariza B.;
(Waltham, MA) ; Skyler; David A.; (Owings Mills,
MD) ; Hardin; John M.; (Hopkinton, MA) |
Assignee: |
Zink Imaging, Inc.
|
Family ID: |
40913229 |
Appl. No.: |
12/750539 |
Filed: |
March 30, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12022969 |
Jan 30, 2008 |
7704667 |
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12750539 |
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11751286 |
May 21, 2007 |
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12022969 |
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11369805 |
Mar 6, 2006 |
7220868 |
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11751286 |
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10788963 |
Feb 27, 2004 |
7008759 |
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11369805 |
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11433808 |
May 12, 2006 |
7829497 |
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12022969 |
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60451208 |
Feb 28, 2003 |
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60680088 |
May 12, 2005 |
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60680212 |
May 12, 2005 |
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Current U.S.
Class: |
347/197 ;
549/344 |
Current CPC
Class: |
C07D 311/02 20130101;
B41M 5/385 20130101; B41M 5/284 20130101; C07D 491/20 20130101;
C07D 493/10 20130101 |
Class at
Publication: |
347/197 ;
549/344 |
International
Class: |
B41J 25/304 20060101
B41J025/304; C07D 493/10 20060101 C07D493/10 |
Claims
1. A thermal imaging member comprising a substrate carrying an
image-forming layer which includes a compound represented by the
formula I: ##STR00004## wherein: R.sub.1, R.sub.3, R.sub.4,
R.sub.5, R.sub.6 and R.sub.7 are each independently selected from
the group consisting of hydrogen, alkyl, preferably having from 1
to 18 carbon atoms, substituted alkyl, alkenyl, substituted
alkenyl, alkynyl, substituted, alkynyl, heterocycloalkyl,
substituted heterocycloalkyl, substituted carbonyl, acylamino,
halogen, nitro, nitrilo, sulfonyl, aryl, substituted aryl,
heteroaryl, substituted heteroaryl, oxygen, substituted oxygen,
nitrogen, substituted nitrogen, sulfur and substituted sulfur;
R.sub.2 is selected from the group consisting of hydrogen, alkyl,
preferably having from 1 to 18 carbon atoms, substituted alkyl,
alkenyl, substituted alkenyl, alkynyl, substituted alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, sulfonyl, aryl, substituted aryl, heteroaryl, substituted
heteroaryl, substituted oxygen, substituted nitrogen and
substituted sulfur; R.sub.8 is absent or selected from the group
consisting of hydrogen, alkyl, preferably having from 1 to 18
carbon atoms, substituted alkyl, alkenyl, substituted alkenyl,
alkynyl, substituted alkynyl, heterocycloalkyl, substituted
heterocycloalkyl, substituted carbonyl, acylamino, halogen, nitro,
nitrilo, sulfonyl, aryl, substituted aryl, heteroaryl, substituted
heteroaryl, oxygen, substituted oxygen, nitrogen, substituted
nitrogen, sulfur and substituted sulfur; R.sub.9, R.sub.10 and
R.sub.11 are independently selected from the group consisting of
hydrogen, alkyl, preferably having from 1 to 18 carbon atoms,
substituted alkyl, alkenyl, substituted alkenyl, alkynyl,
substituted alkynyl, heterocycloalkyl, substituted
heterocycloalkyl, substituted carbonyl, acylamino, halogen, nitro,
nitrilo, sulfonyl, aryl, substituted aryl, heteroaryl, substituted
heteroaryl, oxygen, substituted oxygen, nitrogen, substituted
nitrogen, sulfur and substituted sulfur; R.sub.12, R.sub.13,
R.sub.14 and R.sub.15 are independently selected from the group
consisting of hydrogen, alkyl, preferably having from 1 to 18
carbon atoms, substituted alkyl, alkenyl, substituted alkenyl,
alkynyl, substituted alkynyl, heterocycloalkyl, substituted
heterocycloalkyl, substituted carbonyl, acylamino, aryl,
substituted aryl, heteroaryl, and substituted heteroaryl; R.sub.16,
R.sub.17, R.sub.18 and R.sub.19 are independently selected from the
group consisting of hydrogen, alkyl, preferably having from 1 to 18
carbon atoms, substituted alkyl, alkenyl, substituted alkenyl,
alkynyl, substituted alkynyl, heterocycloalkyl, substituted
heterocycloalkyl, substituted carbonyl, acylamino, halogen, nitro,
nitrilo, sulfonyl, aryl, substituted aryl, heteroaryl, substituted
heteroaryl, oxygen, substituted oxygen, nitrogen, substituted
nitrogen, sulfur and substituted sulfur; and X.sub.1 is carbon or
nitrogen; wherein said compound is in the crystalline form.
2. The thermal imaging member as defined in claim 1 wherein said
compound represented by formula I has a glass transition
temperature of at least 50.degree. C.
3. The thermal imaging member as defined in claim 1 wherein said
image-forming layer further comprises at least one thermal
solvent.
4. The thermal imaging member as defined in claim 3 wherein said
thermal solvent is selected from the group consisting of
diphenylsulfone, 4,4'-dimethyldiphenylsulfone, phenyl
p-tolylsulfone, 4,4'-dichlorodiphenylsulfone,
1,2-bis(2,4-dimethylphenoxy)ethane,
1,4-bis(4-methylphenoxymethyl)benzene, 1,4-bis(benzyloxy)benzene
and mixtures thereof.
5. The thermal imaging member as defined in claim 1 wherein said
image-forming layer further comprises at least one compound
comprising a phenolic grouping.
6. The thermal imaging member as defined in claim 5 wherein said
compound comprising a phenolic grouping is selected from the group
consisting of 2,2'-methylenebis(6-tert-butyl-4-methylphenol),
2,2'-methylenebis(6-tert-butyl-4-ethylphenol),
2,2'-ethylidenebis(4,6-di-tert-butylphenol),
bis[2-hydroxy-5-methyl-3-(1-methylcyclohexyl)phenyl]-methane,
1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate,
2,6-bis[[3-(1,1-dimethylethyl)-2-hydroxy-5-methylphenyl]methyl]-4-methylp-
henol, 2,2'-butylidenebis[6-(1,1-dimethylethyl)-4-methylphenol,
2,2'-(3,5,5-trimethylhexylidene)bis[4,6-dimethyl-phenol],
2,2'-methylenebis[4,6-bis(1,1-dimethylethyl)-phenol,
2,2'-(2-methylpropylidene)bis[4,6-dimethyl-phenol],
1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane,
tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate,
2,2'-thiobis(4-tert-octylphenol), and
3-tert-butyl-4-hydroxy-5-methylphenyl sulfide.
7. A thermal imaging method comprising (a) providing an imaging
member as defined in claim 1; and (b) converting at least a portion
of said compound to an amorphous form in an image-wise pattern
whereby an image is formed.
8. The thermal imaging method as defined in claim 7 wherein step
(b) comprises applying an image-wise pattern of thermal energy to
said imaging member, said thermal energy being sufficient to
convert at least some of said compound to an amorphous form.
9. A compound of formula I ##STR00005## in which: R.sub.1, R.sub.3,
R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are each independently
selected from the group consisting of hydrogen, alkyl, preferably
having from 1 to 18 carbon atoms, substituted alkyl, alkenyl,
substituted alkenyl, alkynyl, substituted, alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, acylamino, halogen, nitro, nitrilo, sulfonyl, aryl,
substituted aryl, heteroaryl, substituted heteroaryl, oxygen,
substituted oxygen, nitrogen, substituted nitrogen, sulfur and
substituted sulfur; R.sub.2 is selected from the group consisting
of aryl, and substituted aryl; R.sub.8, R.sub.9, R.sub.10 and
R.sub.11 are fluorine atoms; R.sub.12 and R.sub.13 are hydrogen
atoms; R.sub.14 and R.sub.15 are identical substituents selected
from the group consisting of alkyl having from 1 to 18 carbon atoms
and substituted alkyl having from 1 to 18 carbon atoms; R.sub.16,
R.sub.17, R.sub.18 and R.sub.19 are independently selected from the
group consisting of hydrogen, alkyl, preferably having from 1 to 18
carbon atoms, substituted alkyl, alkenyl, substituted alkenyl,
alkynyl, substituted alkynyl, heterocycloalkyl, substituted
heterocycloalkyl, substituted carbonyl, acylamino, halogen, nitro,
nitrilo, sulfonyl, aryl, substituted aryl, heteroaryl, substituted
heteroaryl, oxygen, substituted oxygen, nitrogen, substituted
nitrogen, sulfur and substituted sulfur; and X.sub.1 is carbon.
10. The compound of formula I in which R.sub.2 is a
2,4-dimethylphenyl group, R.sub.8, R.sub.9, R.sub.10 and R.sub.11
are fluorine, R.sub.14, R.sub.15 and R.sub.17 are methyl groups,
R.sub.1, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.12,
R.sub.13, R.sub.16, R.sub.18 and R.sub.19 are hydrogen and
X.sub.1is carbon.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of copending U.S.
patent application Ser. No. 11/751,286, filed on May 21, 2007,
entitled "Process for the Preparation of Novel Dyes for use in
Imaging Systems", which is a continuation of U.S. patent
application Ser. No. 11/369,805 filed on Mar. 6, 2006, now U.S.
Pat. No. 7,220,868, which is a continuation of U.S. patent
application Ser. No. 10/788,963 filed on Feb. 27, 2004, now U.S.
Pat. No. 7,008,759, which claims priority from Provisional
Application No. 60/451,208, filed on Feb. 28, 2003. This
application is also a continuation-in-part of U.S. patent
application Ser. No. 11/433,808, filed May 12, 2006, entitled
"Thermal Imaging Members and Methods", which claims the benefit of
priority from U.S. Provisional Application No. 60/680,088, filed
May 12, 2005 and 60/680,212, filed on May 12, 2005. The contents of
the above-referenced applications are incorporated herein by
reference in their entireties.
[0002] This application also related to the following commonly
assigned United States patent applications and patents, the
disclosures of all of which are hereby incorporated by reference
herein in their entirety:
[0003] U.S. Pat. No. 6,801,233 B2 which describes and claims a
thermal imaging system for use in the present invention;
[0004] U.S. Pat. No. 7,008,759 B2 which describes and claims
color-forming compositions for use in the present invention;
[0005] U.S. Pat. No. 7,176,161 B2 which describes and claims
color-forming compositions for use in the present invention;
[0006] U.S. Pat. No. 7,282,317 B2 which describes and claims
color-forming compositions for use in the present invention;
[0007] U.S. patent application Ser. No. 11/400734, filed Apr. 6,
2006, which describes and claims an imaging method for use in the
present invention; and
[0008] U.S. patent application Ser. No. 11/400735, filed Apr. 6,
2006, which describes and claims an imaging method for use in the
present invention; and
[0009] U.S. patent application Ser. No. 11/433808, filed May 12,
2006, entitled "Thermal Imaging Members and Methods".
FIELD OF THE INVENTION
[0010] This invention relates to novel compounds and, more
particularly, to compounds which exhibit one color in the
crystalline form and a second, different color in the liquid, or
amorphous, form. Also described are imaging members and methods,
including thermal imaging members and methods, utilizing the
compounds.
BACKGROUND OF THE INVENTION
[0011] The development of thermal print heads (linear arrays of
individually-addressable resistors) has led to the development of a
wide variety of thermally-sensitive media. In some of these, known
as "thermal transfer" systems, heat is used to move colored
material from a donor sheet to a receiver sheet. Alternatively,
heat may be used to convert a colorless coating on a single sheet
into a colored image, in a process known as "direct thermal"
imaging. Direct thermal imaging has the advantage over thermal
transfer of the simplicity of a single sheet. On the other hand,
unless a fixing step is incorporated, direct thermal systems are
still sensitive to heat after thermal printing. If a stable image
is needed from an unfixed direct thermal system, the temperature
for coloration must be higher than any temperature that the image
is likely to encounter during normal use. A problem arises in that
the higher the temperature for coloration, the less sensitive the
medium will be when printed with the thermal print head. High
sensitivity is important for maximum speed of printing, for
maximizing the longevity of the print head, and for energy
conservation in mobile, battery-powered printers. As described in
more detail below, maximizing sensitivity while maintaining
stability is more easily achieved if the temperature of coloration
of a direct thermal medium is substantially independent of the
heating time.
[0012] Thermal print heads address one line of the image at a time.
For reasonable printing times, each line of the image is heated for
about ten milliseconds or less. Storage of the medium (prior to
printing or in the form of the final image) may need to be for
years, however. Thus, for high imaging sensitivity, a high degree
of coloration is required in a short time of heating, while for
good stability a low degree of coloration is required for a long
time of heating.
[0013] Most chemical reactions speed up with increasing
temperature. Therefore, the temperature required for coloration in
the short heating time available from a thermal print head will
normally be higher than the temperature needed to cause coloration
during the long storage time. Actually reversing this order of
temperatures would be a very difficult task, but maintaining a
substantially time-independent temperature of coloration, such that
both long-time and short-time temperatures for coloration are
substantially the same, is a desirable goal that is achieved by the
present invention.
[0014] There are other reasons why a time-independent coloration
temperature may be desirable. It may, for example, be required to
perform a second thermal step, requiring a relatively long time of
heating, after printing. An example of such a step would be thermal
lamination of an image. The temperature of coloration of the medium
during the time required for thermal lamination must be higher than
the lamination temperature (otherwise the medium would become
colorized during lamination). It would be preferred that the
imaging temperature be higher than the lamination temperature by as
small a margin as possible, as would be the case for
time-independent temperature of coloration.
[0015] Finally, the imaging system may comprise more than one
color-forming layer and be designed to be printed with a single
thermal print-head, as described in the above-mentioned patent
application Ser. No. 10/151,432. In one embodiment of the imaging
system, the topmost color-forming layer forms color in a relatively
short time at a relatively high temperature, while the lower layer
or layers form color in a relatively long time at a relatively low
temperature. An ideal topmost layer for this type of direct thermal
imaging system would have time-independent temperature of
coloration.
[0016] Prior art direct thermal imaging systems have used several
different chemical mechanisms to produce a change in color. Some
have employed compounds that are intrinsically unstable, and which
decompose to form a visible color when heated. Such color changes
may involve a unimolecular chemical reaction. This reaction may
cause color to be formed from a colorless precursor, the color of a
colored material to change, or a colored material to bleach. The
rate of the reaction is accelerated by heat. For example, U.S. Pat.
No. 3,488,705 discloses thermally unstable organic acid salts of
triarylmethane dyes that are decomposed and bleached upon heating.
U.S. Pat. No. 3,745,009 reissued as U.S. Reissue Pat. No. 29,168
and U.S. Pat. No. 3,832,212 disclose heat-sensitive compounds for
thermography containing a heterocyclic nitrogen atom substituted
with an --OR group, for example, a carbonate group, that decolorize
by undergoing homolytic or heterolytic cleavage of the
nitrogen-oxygen bond upon heating to produce an RO+ ion or RO'
radical and a dye base or dye radical which may in part fragment
further. U.S. Pat. No. 4,380,629 discloses styryl-like compounds
that undergo coloration or bleaching, reversibly or irreversibly,
via ring-opening and ring-closing in response to activating
energies. U.S. Pat. No. 4,720,449 describes an intramolecular
acylation reaction that converts a colorless molecule to a colored
form. U.S. Pat. No. 4,243,052 describes pyrolysis of a mixed
carbonate of a quinophthalone precursor that may be used to form a
dye. U.S. Pat. No. 4,602,263 describes a thermally-removable
protecting group that may be used to reveal a dye or to change the
color of a dye. U.S. Pat. No. 5,350,870 describes an intramolecular
acylation reaction that may be used to induce a color change. A
further example of a unimolecular color-forming reaction is
described in "New Thermo-Response Dyes: Coloration by the Claisen
Rearrangement and Intramolecular Acid-Base Reaction Masahiko
Inouye, Kikuo Tsuchiya, and Teijiro Kitao, Angew. Chem. Int. Ed.
Engl. 31, pp. 204-5 (1992).
[0017] In all of the above-mentioned examples, control of the
chemical reaction is achieved through the change in rate that
occurs with changing temperature. Thermally-induced changes in
rates of chemical reactions in the absence of phase changes may
often be approximated by the Arrhenius equation, in which the rate
constant increases exponentially as the reciprocal of absolute
temperature decreases (i.e., as temperature increases). The slope
of the straight line relating the logarithm of the rate constant to
the reciprocal of the absolute temperature is proportional to the
so-called "activation energy". The prior art compounds described
above are coated in an amorphous state prior to imaging, and thus
no change in phase is expected or described as occurring between
room temperature and the imaging temperature. Thus, as employed in
the prior art, these compounds exhibit strongly time-dependent
coloration temperatures. Some of these prior art compounds are
described as having been isolated in crystalline form.
Nevertheless, in no case is there mentioned in this prior art any
change in activation energy of the color-forming reaction that may
occur when crystals of the compounds are melted.
[0018] Other prior art thermal imaging media depend upon melting to
trigger image formation. Typically, two or more chemical compounds
that react together to produce a color change are coated onto a
substrate in such a way that they are segregated from one another,
for example, as dispersions of small crystals. Melting, either of
the compounds themselves or of an additional fusible vehicle,
brings them into contact with one another and causes a visible
image to be formed. For example, a colorless dye precursor may form
color upon heat-induced contact with a reagent. This reagent may be
a Bronsted acid, as described in "Imaging Processes and Materials",
Neblette's Eighth Edition, J. Sturge, V. Walworth, A. Shepp, Eds.,
Van Nostrand Reinhold, 1989, pp. 274-275, or a Lewis acid, as
described for example in U.S. Pat. No. 4,636,819. Suitable dye
precursors for use with acidic reagents are described, for example,
in U.S. Pat. No. 2,417,897, South African Patent 68-00170, South
African Patent 68-00323 and Ger. Off enlegungschrift 2,259,409.
Further examples of such dyes may be found in "Synthesis and
Properties of Phthalide-type Color Formers", by In a Fletcher and
Rudolf Zink, in "Chemistry and Applications of Leuco Dyes",
Muthyala Ed., Plenum Press, New York, 1997. The acidic material may
for example be a phenol derivative or an aromatic carboxylic acid
derivative. Such thermal imaging materials and various combinations
thereof are now well known, and various methods of preparing
heat-sensitive recording elements employing these materials also
are well known and have been described, for example, in U.S. Pat.
Nos. 3,539,375, 4,401,717 and 4,415,633. U.S. Pat. Nos. 4,390,616
and 4,436,920 describe image forming members comprising materials
similar to those of the present invention. The materials described
therein are fluoran dyes for use in conjunction with a developer,
and there is not report of image formation upon melting in the
absence of a developer.
[0019] Prior art systems in which at least two separate components
are mixed following a melting transition suffer from the drawback
that the temperature required to form an image in a very short time
by a thermal print-head may be substantially higher than the
temperature required to colorize the medium during longer periods
of heating. This difference is caused by the change in the rate of
the diffusion needed to mix the molten components together, which
may become limiting when heat is applied for very short periods.
The temperature may need to be raised well above the melting points
of the individual components to overcome this slow rate of
diffusion. Diffusion rates may not be limiting during long periods
of heating, however, and the temperature at which coloration takes
place in these cases may actually be less than the melting point of
either individual component, occurring at the eutectic melting
point of the mixture of crystalline materials.
[0020] As the state of the art in imaging systems advances and
efforts are made to provide new imaging systems that can meet new
performance requirements, and to reduce or eliminate some of the
undesirable characteristics of the known systems, it would be
advantageous to have new compounds which can be used as
image-forming materials in imaging systems, including thermal
imaging systems.
SUMMARY OF THE INVENTION
[0021] It is therefore an object of this invention to provide novel
compounds.
[0022] Another object of the invention is to provide compounds
which exhibit different colors when in the crystalline form and in
the liquid form.
[0023] Yet another object of the invention is to provide imaging
members and methods, including thermal imaging members and methods,
which utilize the novel compounds.
[0024] The present invention provides novel rhodamine compounds
that are useful as image dyes in imaging systems. According to one
aspect of the invention there are provided novel dye compounds
which exhibit a first color when in the crystalline form and a
second color, different from the first color, when in the liquid,
amorphous form.
[0025] In one embodiment of the invention there are provided novel
compounds which are represented by formula I
##STR00001##
wherein:
[0026] R.sub.1, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are
each independently selected from the group consisting of hydrogen,
alkyl, preferably having from 1 to 18 carbon atoms, substituted
alkyl, alkenyl, substituted alkenyl, alkynyl, substituted, alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, acylamino, halogen, nitro, nitrilo, sulfonyl, aryl,
substituted aryl, heteroaryl, substituted heteroaryl, oxygen,
substituted oxygen, nitrogen, substituted nitrogen, sulfur and
substituted sulfur;
[0027] R.sub.2 is selected from the group consisting of hydrogen,
alkyl, preferably having from 1 to 18 carbon atoms, substituted
alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, sulfonyl, aryl, substituted aryl, heteroaryl, substituted
heteroaryl, substituted oxygen, substituted nitrogen and
substituted sulfur;
[0028] R.sub.8 is absent or selected from the group consisting of
hydrogen, alkyl, preferably having from 1 to 18 carbon atoms,
substituted alkyl, alkenyl, substituted alkenyl, alkynyl,
substituted alkynyl, heterocycloalkyl, substituted
heterocycloalkyl, substituted carbonyl, acylamino, halogen, nitro,
nitrilo, sulfonyl, aryl, substituted aryl, heteroaryl, substituted
heteroaryl, oxygen, substituted oxygen, nitrogen, substituted
nitrogen, sulfur and substituted sulfur;
[0029] R.sub.9, R.sub.10 and R.sub.11 are independently selected
from the group consisting of hydrogen, alkyl, preferably having
from 1 to 18 carbon atoms, substituted alkyl, alkenyl, substituted
alkenyl, alkynyl, substituted alkynyl, heterocycloalkyl,
substituted heterocycloalkyl, substituted carbonyl, acylamino,
halogen, nitro, nitrilo, sulfonyl, aryl, substituted aryl,
heteroaryl, substituted heteroaryl, oxygen, substituted oxygen,
nitrogen, substituted nitrogen, sulfur and substituted sulfur;
[0030] R.sub.12, R.sub.13, R.sub.14 and R.sub.15 are independently
selected from the group consisting of hydrogen, alkyl, preferably
having from 1 to 18 carbon atoms, substituted alkyl, alkenyl,
substituted alkenyl, alkynyl, substituted alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, acylamino, aryl, substituted aryl, heteroaryl, and
substituted heteroaryl;
[0031] R.sub.16, R.sub.17, R.sub.18 and R.sub.19 are independently
selected from the group consisting of hydrogen, alkyl, preferably
having from 1 to 18 carbon atoms, substituted alkyl, alkenyl,
substituted alkenyl, alkynyl, substituted alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, acylamino, halogen, nitro, nitrilo, sulfonyl, aryl,
substituted aryl, heteroaryl, substituted heteroaryl, oxygen,
substituted oxygen, nitrogen, substituted nitrogen, sulfur and
substituted sulfur; and X.sub.1 is carbon or nitrogen.
[0032] In a preferred group of compounds represented by formula I,
R.sub.8, R.sub.9, R.sub.10 and R.sub.11 are halogen and R.sub.1,
R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.5, R.sub.7, R.sub.12,
R.sub.13, R.sub.14, R.sub.15, R.sub.16, R.sub.17, R.sub.18 and
R.sub.19 are as previously defined and X.sub.1 is carbon.
[0033] The conversion to the liquid form can be carried out by
applying heat to the compounds and therefore the compounds are
useful in thermal imaging members used in thermal imaging methods.
In such thermal imaging methods thermal energy may be applied to
the thermal imaging members by any of the techniques known in
thermal imaging such as from a thermal print head, a laser, a
heated stylus, etc. In another embodiment, the conversion to the
liquid form may be effected by applying a solvent for the
crystalline solid such as from an ink jet imaging apparatus to at
least partially dissolve the crystalline material. In another
embodiment, one or more thermal solvents, which are crystalline
materials, can be incorporated in the thermal imaging member. The
crystalline thermal solvent(s), upon being heated, melt and
dissolve or liquefy, and thereby convert, at least partially, the
crystalline image-forming material to the liquid amorphous form to
form the image.
[0034] The compounds of the invention may be incorporated in any
suitable thermal imaging members. Typical suitable thermal imaging
members generally comprise a substrate carrying at least one
image-forming layer including a compound in the crystalline form,
which can be converted, at least partially to a liquid in the
amorphous form, the liquid having intrinsically a different color
from the crystalline form. The thermal imaging member may be
monochrome or multicolor and the temperature at which an image is
formed in at least one of the image-forming layers is time
independent.
[0035] Preferred thermal imaging members according to the invention
are those having the structures described in prior co-pending
commonly assigned U.S. patent application Ser. No. 09/745,700 filed
Dec. 20, 2000, now U.S. Pat. No. 6,537,410 B1 which is hereby
incorporated herein by reference in its entirety and made a part of
this application.
[0036] Other preferred thermal imaging members are those having the
structures described in prior, co-pending commonly assigned U.S.
patent application Ser. No. 10/151,432 filed May 20, 2002 which is
hereby incorporated herein by reference in its entirety and made a
part of this application.
[0037] Further preferred thermal imaging members are those having
the structures described in U.S. Pat. No. 6,054,246 which is hereby
incorporated herein by reference in its entirety and made a part of
this application.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Compounds in the crystalline state commonly have properties,
including color, that are very different from those of the same
compounds in an amorphous form. In a crystal, a molecule is
typically held in a single conformation (or, more rarely, in a
small number of conformations) by the packing forces of the
lattice. Likewise, if a molecule can exist in more than one
interconverting isomeric forms, only one of such isomeric forms is
commonly present in the crystalline state. In amorphous form or
solution, on the other hand, the compound may explore its whole
conformational and isomeric space, and only a small proportion of
the population of individual molecules of the compound may at any
one time exhibit the particular conformation or isomeric form
adopted in the crystal. Compounds of the present invention exhibit
tautomerism in which at least one tautomeric form is colorless, and
at least another tautomeric form is colored. The crystalline form
of compounds of the present invention comprises predominantly the
colorless tautomer.
[0039] A first embodiment of the invention is a compound
represented by Formula I as described above.
[0040] A first embodiment of the invention is a compound whose
colorless tautomer is represented by formula I as described
above.
[0041] Representative compounds according to the invention are
those of formula I in which R.sub.1, R.sub.3, R.sub.4, R.sub.5,
R.sub.6, R.sub.7, R.sub.12, R.sub.16 , R.sub.18 and R.sub.19 are
hydrogen, X.sub.1 is carbon, and the other substituents are as
shown in Table I:
TABLE-US-00001 TABLE I Com- R.sub.8, R.sub.9, R.sub.13, pound
R.sub.2 R.sub.10, R.sub.11 R.sub.14, R.sub.15 R.sub.17 I
C.sub.6H.sub.5 Cl Me H II 4-(O-2-ethyl-1-hexyl)C.sub.6H.sub.4 Cl H
H III 3,4-dioctyloxy-C.sub.6H.sub.3 Cl H H IV
4-(2-hydroxy-1-decyloxy)-C.sub.6H.sub.4 Cl H H V
3,4-dioctyloxy-C.sub.6H.sub.3 Cl H OMe VI
2-isopropyl-C.sub.6H.sub.4 F H H VII
2-Methyl-4-decyloxy-C.sub.6H.sub.3 F H H VIII
2-Methyl-4-decyloxy-C.sub.6H.sub.3 F H Me IX
2-Methyl-4-octadecyloxy-C.sub.6H.sub.3 F H H
[0042] Preferred compounds according to the invention are III, VII
and VIII.
Definitions
[0043] The term "alkyl" as used herein refers to saturated
straight-chain, branched-chain or cyclic hydrocarbon radicals.
Examples of alkyl radicals include, but are not limited to, methyl,
ethyl, propyl, isopropyl, n-butyl, tert-butyl, neopentyl, n-hexyl,
cyclohexyl, n-octyl, n-decyl, n-dodecyl and n-hexadecyl
radicals.
[0044] The term "alkenyl" as used herein refers to unsaturated
straight-chain, branched-chain or cyclic hydrocarbon radicals.
Examples of alkenyl radicals include, but are not limited to,
allyl, butenyl, hexenyl and cyclohexenyl radicals.
[0045] The term "alkynyl" as used herein refers to unsaturated
hydrocarbon radicals having at least one carbon-carbon triple bond.
Representative alkynyl groups include, but are not limited to,
ethynyl, 1-propynyl, 1-butynyl, isopentynyl, 1,3-hexadiynyl,
n-hexynyl, 3-pentynyl, 1-hexen-3-ynyl and the like.
[0046] The terms "halo" and "halogen," as used herein, refer to an
atom selected from fluorine, chlorine, bromine and iodine.
[0047] The term "aryl," as used herein, refers to a mono-, bicyclic
or tricyclic carbocyclic ring system having one, two or three
aromatic rings including, but not limited to, phenyl, naphthyl,
anthryl, azulyl, tetrahydronaphthyl, indanyl, indenyl and the
like.
[0048] The term "heteroaryl," as used herein, refers to a cyclic
aromatic radical having from five to ten ring atoms of which one
ring atom is selected from S, O and N; zero, one or two ring atoms
are additional heteroatoms independently selected from S, O and N;
and the remaining ring atoms are carbon, the radical being joined
to the rest of the molecule via any of the ring atoms, such as, for
example, pyridinyl, pyrazinyl, pyrimidinyl, pyrrolyl, pyrazolyl,
imidazolyl, thiazolyl, oxazolyl, isooxazolyl, thiadiazolyl,
oxadiazolyl, thiophenyl, furanyl, quinolinyl, isoquinolinyl, and
the like.
[0049] The term "heterocycloalkyl," as used herein, refers to a
non-aromatic 3-, 4-, 5-, 6- or 7-membered ring or a bi- or
tri-cyclic group comprising fused six-membered rings having between
one and three heteroatoms independently selected from oxygen,
sulfur and nitrogen, wherein (i) each 5-membered ring has 0 to 1
double bonds and each 6-membered ring has 0 to 2 double bonds, (ii)
the nitrogen and sulfur heteroatoms may optionally be oxidized,
(iii) the nitrogen heteroatom may optionally be quaternized, and
(iv) any of the above heterocyclic rings may be fused to a benzene
ring. Representative heterocycles include, but are not limited to,
pyrrolidinyl, pyrazolinyl, pyrazolidinyl, imidazolinyl,
imidazolidinyl, piperidinyl, piperazinyl, oxazolidinyl,
isoxazolidinyl, morpholinyl, thiazolidinyl, isothiazolidinyl, and
tetrahydrofuryl.
[0050] The term "carbonyl" as used herein refers to a carbonyl
group, attached to the parent molecular moiety through the carbon
atom, this carbon atom also bearing a hydrogen atom, or in the case
of a "substituted carbonyl" a substituent as described in the
definition of "substituted" below.
[0051] The term "acyl" as used herein refers to groups containing a
carbonyl moiety. Examples of acyl radicals include, but are not
limited to, formyl, acetyl, propionyl, benzoyl and naphthyl.
[0052] The term "alkoxy", as used herein, refers to a substituted
or unsubstituted alkyl, alkenyl or heterocycloalkyl group, as
previously defined, attached to the parent molecular moiety through
an oxygen atom. Examples of alkoxy radicals include, but are not
limited to, methoxy, ethoxy, propoxy, isopropoxy, n-butoxy,
tert-butoxy, neopentoxy and n-hexoxy.
[0053] The term `aryloxy" as used herein refers to a substituted or
unsubstituted aryl or heteroaryl group, as previously defined,
attached to the parent molecular moiety through an oxygen atom.
Examples of aryloxy include, but are not limited to, phenoxy,
p-methylphenoxy, naphthoxy and the like.
[0054] The term "alkylamino", as used herein, refers to a
substituted or unsubstituted alkyl, alkenyl or heterocycloalkyl
group, as previously defined, attached to the parent molecular
moiety through a nitrogen atom. Examples of alkylamino radicals
include, but are not limited to, methylamino, ethylamino,
hexylaminoand dodecylamino.
[0055] The term "arylamino", as used herein, refers to a
substituted or unsubstituted aryl or heteroaryl group, as
previously defined, attached to the parent molecular moiety through
a nitrogen atom.
[0056] The term "substituted" as used herein in phrases such as
"substituted alkyl", "substituted alkenyl", "substituted aryl",
"substituted heteroaryl", "substituted heterocycloalkyl",
"substituted carbonyl", "substituted alkoxy", "substituted acyl",
"substituted amino", "substituted aryloxy", and the like, refers to
independent replacement of one or more of the hydrogen atoms on the
substituted moiety with substituents independently selected from,
but not limited to, alkyl, alkenyl, heterocycloalkyl, alkoxy,
aryloxy, hydroxy, amino, alkylamino, arylamino, cyano, halo,
mercapto, nitro, carbonyl, acyl, aryl and heteroaryl groups.
[0057] According to the invention, there have been provided
molecules exhibiting tautomerism in which at least one tautomeric
form is colorless, and at least another tautomeric form is colored.
Crystallization of the equilibrating mixture of the two tautomeric
forms is carried out so as to produce colorless crystals. The
solvent chosen to perform the crystallization will typically be one
of such polarity (and other chemical properties, such as
hydrogen-bonding ability) that the pure colorless crystal form is
favored, either in the equilibrium between the colorless and
colored forms in solution, or in having lower solubility in the
solvent than the colored form. The choice of solvent is usually
determined empirically for a particular mixture of tautomers.
[0058] Upon conversion of the pure crystalline colorless form, the
equilibrium between the two tautomers is re-established in the
resulting amorphous (liquid) phase. The proportion of the amorphous
material that is colored (i.e., the proportion that is in the
colored tautomeric form) may vary, but is preferably at least about
10%.
[0059] The colored and colorless tautomeric forms of the molecules
of the present invention must meet certain criteria for image
quality and permanence. The colorless form, which is preferably the
crystalline form, should have minimal visible absorption. It should
be stable to light, heating below the melting point, humidity, and
other environmental factors such as ozone, oxygen, nitrogen oxides,
fingerprint oils, etc. These environmental factors are well known
to those skilled in the imaging art. The colored, amorphous form
should be stable also to the above mentioned conditions, and in
addition should not recrystallize to the colorless form under
normal handling conditions of the image. The colored form should
have a spectral absorption appropriate for digital color rendition.
Typically, the colored form should be yellow (blue-absorbing),
magenta (green-absorbing), cyan (red absorbing), or black, without
undue absorption in an unintended spectral region. For
nonphotographic applications, however, it may be required that the
colored form not be one of the subtractive primary colors, but
rather a particular spot color (for example, orange, blue,
etc.).
[0060] The compounds of the invention may be prepared by synthetic
processes which are known to those skilled in the art, particularly
in view of the state of the art and the specific preparatory
examples provided below herein.
[0061] Symmetrical rhodamine dyes can be prepared in one step from
3',6'-dichlorofluorans by reacting two equivalents of an aromatic
or aliphatic amine as described in U.S. Pat. No. 4,602,263, British
Patent No. GB2311075 and German Patent No. DE81056. The novel
unsymmetrical rhodamine dyes in this application require a more
controlled synthetic pathway in which one equivalent of an indoline
is reacted selectively with the 3',6'-dichlorofluoran using
aluminum chloride as a catalyst to produce
3'-chloro-6'-indolinofluorans. These products are isolated and
purified prior to reacting with a second equivalent of an aromatic
or aliphatic amine. Zinc chloride is used as the catalyst for the
second addition. German Patent No. DE139727 describes the selective
addition of anilines to 3',6'-dichlorofluorans to produce
3'-chloro-6'-arylaminofluorans using a mixture of zinc chloride and
zinc oxide at 160.degree. C.
[0062] To optimize the chromophore, melting point, degree of
coloration, light stability and solubility of the dyes in this
application a variety of indolines, anilines and dichlorofluorans
are utilized.
[0063] 5-methoxyindoline and 5-methylindoline are prepared from the
corresponding indoles by reduction with sodium cyanoborohydride in
acetic acid. 2,3,3-trimethylindoline is prepared from
2,3,3-trimethylindolenine by hydrogenation.
[0064] The aromatic amines used in this application are synthesized
from 4-nitro-3-methylphenol, 4-nitrophenol and 4-nitrocatechol. The
anions of the phenols are generated in dimethylformamide with
potassium carbonate and alkylated with a variety of alkylating
agents such as 1-bromodecane, 1-bromooctadecane,
1-bromo-2-ethylhexane. Alternatively, the sodium salts of the
phenols are alkylated with 1,2-epoxyalkanes using
tetrabutylammonium sulfate in a boiling mixture of toluene and
water. The resulting 4-nitrophenylethers are reduced to the
corresponding anilines using standard methods such as
hydrogenation, iron powder, hydrazine or ammonium formate.
[0065] The 3',6'-dichlorofluorans are synthesized from the
corresponding fluoresceins using thionyl chloride and
dimethylformamide in a variation of the method of Hurd described in
the Journal of the Amer. Chemical Soc. 59, 112 (1937).
4,5,6,7-tetrafluorofluorescein is prepared according to the
procedure of Haugland described in the Journal of Organic
Chemistry, 62, 6469 (1997).
[0066] The thermal imaging members of the invention can be direct
thermal imaging members wherein an image is formed in the member
itself or they can be thermal transfer imaging members whereby
image-forming material is transferred to an image-receiving member.
The melting point of the molecules used in direct thermal imaging
members of the present invention is preferably in the range of
about 60.degree. C. to about 300.degree. C. Melting points lower
than about 60.degree. C. lead to direct thermal imaging members
that are unstable to temperatures occasionally encountered during
handling of the members before or after imaging, while melting
temperatures above about 300.degree. C. render the compounds
difficult to colorize with a conventional thermal print head. It
should be noted, however, that there are uses for certain novel
compounds of the present invention that do not require the use of
thermal print heads (for example, laser imaging).
[0067] The colors formed by preferred compounds of the present
invention are typically cyan, which is to say that the maximum
absorption of the preferred compounds in the amorphous state lies
between about 600 and about 700 nm. It has been found that the
wavelength of maximum absorption of the colored form of compounds
of the present invention is longer when substituents R.sub.8,
R.sub.9, R.sub.10 and R.sub.11 of formula I are
electron-withdrawing relative to hydrogen. Dyes with relatively
short maximum absorption wavelengths may appear blue, rather than
cyan, and for this reason substituents R.sub.8, R.sub.9, R.sub.10
and R.sub.11 of formula I are preferred to be highly
electron-withdrawing, and preferably halogen, when X.sub.1 of
formula I is a carbon atom and the color cyan is desired.
[0068] To form a direct thermal imaging system, the crystalline,
colorless form of the compounds of the invention is made into a
dispersion in a solvent in which the compound is insoluble or only
sparingly soluble, by any of the methods known in the art for
forming dispersions. Such methods include grinding, attriting, etc.
The particular solvent chosen will depend upon the particular
crystalline material. Solvents that may be used include water,
organic solvents such as hydrocarbons, esters, alcohols, ketones,
nitriles, and organic halide solvents such as chlorinated and
fluorinated hydrocarbons. The dispersed crystalline material may be
combined with a binder, which may be polymeric. Suitable binders
include water-soluble polymers such as poly(vinyl alcohol),
poly(vinylpyrollidone) and cellulose derivatives, water-dispersed
latices such as styrene/butadiene or poly(urethane) derivatives, or
alternatively hydrocarbon-soluble polymers such as polyethylene,
polypropylene, copolymers of ethylene and norbornene, and
polystyrene. This list is not intended to be exhaustive, but is
merely intended to indicate the breadth of choice available for the
polymeric binder. The binder may be dissolved or dispersed in the
solvent.
[0069] Following preparation of the dispersion of the compound of
the present invention, and optional addition of a polymeric binder,
the resultant fluid is coated onto a substrate using any of the
techniques well-known in the coating art. These include slot,
gravure, Meyer rod, roll, cascade, spray, and curtain coating
techniques. The image-forming layer so formed is optionally
overcoated with a protective layer or layers.
[0070] If materials of the present invention are used to prepare an
imaging medium of the type described in copending U.S. patent
application Ser. No. 10/151,432 filed May 20, 2002 the process
described above is followed for each of the imaging layers.
Successive layers may be coated sequentially, in tandem, or in a
combination of sequential and tandem coatings.
EXAMPLES
[0071] The invention will now be described further in detail with
respect to specific embodiments by way of examples, it being
understood that these are intended to be illustrative only and the
invention is not limited to the materials, amounts, procedures and
process parameters, etc. recited therein. All parts and percentages
recited are by weight unless otherwise specified.
Example 1
Synthesis of Intermediates
[0072] Step 1A. Alkylation of 4-nitrocatechol 4-Nitrocatechol
(23.26 g, 0.15 mol) and potassium carbonate (124.38 g, 0.9 mol)
were placed in a one liter 3-neck flask fitted with a mechanical
stirrer. Anhydrous dimethylformamide (350 mL) was added to this
mixture followed by the addition to the suspension, dropwise, of
1-bromo octane (63.73 g, 0.33 mol). The reaction mixture was heated
at 110.degree. C. for 24 hours. The reaction was followed by TLC
(2% methanol in methylene chloride). After the completion of the
reaction the contents were cooled and poured dropwise with stirring
into ice-water (1 L). The mixture was stirred for one hour and
filtered. The collected solid was washed thoroughly with water,
air-dried and then dried in vacuo at 30.degree. C. This process
produced brown crystals: (54.8 g, 0.144 mol, 96% yield). These
crystals were used without further purification.
Step 1B. Synthesis of 3,4-dioctyloxyaniline
[0073] 3,4-Dioctyloxynitrobenzene (25.25 g, 0.067 mol) was
dissolved in ethyl acetate (250 mL) in a Parr bottle. 10% Pd on
charcoal (3.5 g) was added and the mixture was hydrogenated (5-6
hr) at 50 psi until the hydrogen uptake ceased. The reaction
mixture was filtered and evaporated. The aniline was obtained as a
dark syrup. (22.5 g, 0.064 mol, 97% yield). The structure was
corroborated by NMR and mass spectroscopy.
Step 1C. Synthesis of 2-methyl-4-decyloxynitro benzene
[0074] To a solution of 3-methyl-4-nitrophenol (45 g, 0.294 mol) in
dimethylformamide (270 mL) there were added 1-bromodecane (65 g,
0.294 mol) and potassium carbonate (121.8 g, 0.882 mol). The
reaction mixture was heated to 115.degree. C. and stirred at that
temperature for 48 hours. The reaction mixture was cooled and
poured into water (4 L), stirred for 0.5 hour and extracted with
two portions of ethyl acetate (1.5 L and 600 mL). The combined
organic extracts were washed with 5% aqueous solution sodium
bicarbonate (1 L), water (1 L and 0.5 L), dried over sodium sulfate
and concentrated to give the crude product (90 g, 0.294 mol, 100%
yield). This product was used in the next step without
purification.
Step 1D. Synthesis of 2-methyl-4-decyloxyaniline
[0075] The mixture of crude 2-methyl-4-decyloxynitrobenzene (90 g,
0.294 mol ), methanol (246 mL), concentrated hydrochloric acid (159
mL) and dioxane (70 mL) was heated to 75.degree. C. Iron powder
(49.9 g, 0.89 mol) was added in small portions with vigorous
stirring. After the addition was complete the reaction mixture was
stirred at 75.degree. C. for another 20 minutes and poured warm
into water (3 L), stirred for 30 minutes and the pH adjusted to
11.0 by addition of aqueous potassium carbonate solution.
Dichloromethane (3 L) was added and the mixture was stirred
intensively for 1 hour. The layers were separated and the organic
layer dried over sodium sulfate and passed through a thin pad of
silica gel. The solvent was evaporated to dryness to give a brown
oil (58.5 g, 0.22 mol, 76% yield).
Step 1E. Synthesis of 2-methyl-4-octadecyloxynitrobenzene:
[0076] 1-Bromooctadecane (43.54 g, 0.131 mol) and potassium
carbonate (54.15 g, 0.392 mol) were added to a solution of
3-methyl-4-nitrophenol (20 g, 0.131 mol) in dimethylformamide (120
mL) The reaction mixture was heated to 110.degree. C. and stirred
at this temperature for 60 hours. The reaction mixture was cooled
and poured into water (2 L), stirred for 0.5 hour and extracted
with methylene chloride (1 L). The organic extract was washed with
5% aqueous solution sodium bicarbonate (0.5 L), water (2.times.0.6
L), dried over sodium sulfate and concentrated to give (60 g) of
crude product. This product was used in the next step without
purification.
Step 1F. Synthesis of 2-methyl-4-octadecyloxyaniline
[0077] The mixture of crude 2-methyl-4-octadecyloxynitrobenzene (30
g, ca. 0.065 mol), methanol (55 mL), concentrated hydrochloric acid
(40.5 mL) and dioxane (50 mL) was heated to 85.degree. C. Iron
powder (11.2 g, 0.20 mol) was added in small portions with
intensive stirring. After the addition was complete the reaction
mixture was stirred at 85.degree. C. for another 3 hours and poured
warm into water (800 mL), stirred for 30 minutes and the pH
adjusted to 10.0 by addition of aqueous potassium carbonate
solution. Dichloromethane (1.0 L) was added and mixture was stirred
intensively for 1 hour. The layers were separated and the organic
layer was washed with water (2.times.500 mL) and dried over sodium
sulfate. The solvent was evaporated to give an oil (20 g, 0.053
mol, 82% yield), which solidified on standing. The structure of
this material was corroborated by proton NMR and mass
spectroscopy.
Step 1G. Synthesis of 2-ethyl-1-hexyloxynitro benzene
[0078] 4-Nitrophenol (10 g, 72 mmol) and potassium carbonate (30.4
g, 0.22 mol) were added to dimethylformamide (80 mL) at room
temperature and the mixture was stirred with heating at 100.degree.
C. for 2 hours. 2-Ethyl-1-hexyl bromide (16.7 g, 86 mmol) was
slowly added to the mixture for 20 minutes. After the addition the
mixture was further stirred at 150.degree. C. for 3 hours. After
cooling, the reaction mixture was poured into water (500 mL) and
then the mixture was extracted with methylene chloride. After
evaporation of solvent, the residual product was isolated as an oil
in high yield (18 g, 71.6 mmol, 99%
Step 1H. Synthesis of 2-ethyl-1-hexyloxy aniline
[0079] 2-Ethyl-1-hexyloxynitro benzene (18 g, 72 mmol) was
dissolved in isopropanol (80 mL) and 10% Pd/C (1 g) was slowly
added to the mixture in a Parr pressure bottle. The mixture was
hydrogenated at 40 psi for 5 hours and the mixture was filtered to
remove Pd/C followed by evaporation of the solvent to give the oily
product in quantitative yield (15.9 g, 72 mmol, 100% yield).
Step 1I. Synthesis of 4-(2-hydroxy-1-decyloxy)nitrobenzene
[0080] The sodium salt of 4-nitrophenol (28.19 g, 0.175 mol) was
dissolved in water (50 mL) and toluene (300 mL) and
tetrabutylammonium sulfate (6.0 g) was added. 1,2-Epoxydecane (27.3
g, 0.175 mol) was added to this mixture and the reaction was heated
at 100.degree. C. for 5 days. The toluene layer was separated and
washed with water (4.times.75 mL), 1N hydrochloric acid (2.times.75
mL) and water (75 mL). The organic layer was dried over sodium
sulfate, filtered and the solvent removed. The crude product was
purified by silica gel chromatography (2-3% methanol/methylene
chloride) to afford 4-(2-hydroxy-1-decyloxy)nitrobenzene as a pale
oil (20 g, 0.68 mol, 39% yield).
Step 1J. Synthesis of 4-(2-hydroxy-1-decyloxy)aniline
[0081] 4-(2-hydroxy-1-decyloxy)nitrobenzene (20 g, 0.68 mol) was
dissolved in ethyl acetate (200 mL) and 10% palladium on carbon
(2.5 g) was added to a Parr pressure bottle. The contents were then
hydrogenated at 50 psi until hydrogen uptake ceased. The catalyst
was removed by suction filtration through a pad of Celite. Removal
of solvent afforded 4-(2-hydroxy-1-decyloxy)aniline in quantitative
yield (18.0 g, 0.68 mol, 100% yield) as a tan solid. The structure
was confirmed by NMR and mass spectroscopy.
Step 1K. Synthesis of 5-methoxyindoline
[0082] 5-Methoxyindole (50 g, 0.34 mol) was dissolved in glacial
acetic acid (500 mL) in a 3 L 3-necked flask fitted with a
mechanical stirrer, a dropping funnel and a thermometer. The
solution was cooled to 10-12.degree. C. with an ice bath and sodium
cyanoborohydride (64 g, 1.0 mol) was added in portions while
ensuring the temperature remained at or below 15-16.degree. C.
After the addition was complete the cooling bath was removed and
the reaction was warmed to ambient temperature for 0.5 hour. TLC
(1:1 EtOAc/hexane) confirmed a complete reaction. The reaction was
cooled to 5-10.degree. C. and 50% aqueous sodium hydroxide was
added until the pH was 8-10. The product oiled out and was
extracted with ethyl acetate (3.times.700 mL). The combined organic
layers were washed with water (2.times.500 mL) and brine (400 mL),
dried over anhydrous potassium carbonate, filtered and concentrated
to afford 5-methoxyindoline (50 g, 0.337 mol, 99% yield) as a thick
oil. This product was used without further purification. The
structure was corroborated by NMR spectroscopy.
Step 1L. Synthesis of 5-methylindoline
[0083] 5-Methylindoline was prepared from 5-methylindole using the
procedure described for the preparation of 5-methoxyindoline.
5-Methylindole (11 g, 0.0835 mol) in glacial acetic acid (150 mL)
in a 1 L 3-necked flask was reduced at 10-15.degree. C. with sodium
cyanoborohydride (15.8 g, 0.251 mol). Extraction with ethyl acetate
provided 5-methylindoline (11 g, 0.0832 mol, 99% yield) as a thick
oil which was used without further purification. The structure was
corroborated by NMR spectroscopy.
Step 1M. Synthesis of 3',6',4,5,6,7-hexachlorofluoran
[0084] Acetonitrile (680 mL), dimethylformamide (7 mL),
tetrachlorofluorescein (170 g, 0.36 mol) and thionyl chloride (215
g, 1.8 mol) were added to a 3-liter 3-neck round bottom flask
fitted with a mechanical stirrer, condenser and nitrogen inlet
tube. Upon heating, a solution was briefly obtained followed by
gradual crystallization of the product. The mixture was further
heated at reflux (72.degree. C.) for six hours. After cooling to
room temperature, water (100 mL) was slowly and carefully added.
The product was filtered and washed well with acetonitrile. Air
drying provided a pale violet solid (141.5 g, 0.279 mol, 77%
yield). The crude product was stirred in dimethylformamide (425
mL), heated to 100.degree. C., and allowed to stand overnight. The
pale violet crystals were filtered, washed with dimethylformamide
followed by methanol and dried under vacuum at 60.degree. C. to
provide hexachlorofluoran (98.7 g, 0.195 mol, 54% yield). Assay by
HPLC was 97% by area.
Step 1N. Synthesis of 3'-indolino-6',4,5,6,7-pentachlorofluoran
[0085] Hexachlorofluoran (5.07 g, 10 mmol), 2,6-lutidine (1.07 g,
10 mmol), aluminum chloride (9.33 g, 70 mmol) and sulfolane (50 mL)
were added to a 100 mL 3-neck round bottom flask fitted with a
mechanical stirrer, condenser, thermometer and nitrogen inlet tube.
The mixture was heated to 100.degree. C. and indoline (1.19 g,
lOmmol) was added. The temperature was raised to 180.degree. C. and
heating continued for 6 hours. After cooling to room temperature,
the mixture was poured into cold water (250 mL) with rapid
agitation. The blue-gray solid was filtered, washed with water and
air-dried providing the crude product (5 g). The crude product was
stirred in dimethylformamide (20 mL), heated to 100.degree. C. and
allowed to stand overnight. The resulting pale green solid was
filtered, washed first with dimethylformamide followed by methanol
and dried under vacuum at 60.degree. C. to provide
3-indolinopentachlorofluoran (3.60 g, 6.1 mmol, 61% yeld). Assay by
HPLC was 97% by area.
Step 1P. Synthesis of
3'-(5-methoxyindolino)-6',4,5,6,7-pentachlorofluoran
[0086] Hexachlorofluoran (20 g, 0.0394 mol), aluminum chloride
(20.8 g, 0.156 mol) and sulfolane (100 g) were added to a 250 mL
3-neck round bottom flask fitted with a mechanical stirrer,
condenser, thermometer and nitrogen inlet tube. The mixture was
heated to 120.degree. C. and 5-methoxyindoline (12 g, 0.081 mol)
was added. The reaction mixture was heated overnight at 120.degree.
C. After cooling to room temperature, the mixture was poured into
cold water (1 L) with rapid agitation. The solid was filtered,
washed with water and air-dried for several days followed by vacuum
drying at 70.degree. C. to give the crude product (25.5 g, 0.041
mol, 104% yield) which was used without further purification.
Step 1Q. Synthesis of 4,5,6,7-tetrafluorofluorescein
[0087] Using a mechanical stirrer, tetrafluorophthalic anhydride
(50 g, 0.227 mol) was dissolved in methanesulfonic acid (221 mL).
The anhydride dissolved completely as the temperature reached
40.degree. C. When the temperature had reached 120.degree. C.,
resorcinol (62.3 g, 0.568 mol) was added in 3 portions giving
enough time between additions for the material to go into solution.
The solution turned pale red. An HPLC of the reaction mixture was
taken at the start of the reaction and every hour thereafter. The
reaction was complete after three hours. Heating was stopped and
the reaction mixture was allowed to cool to ambient temperature.
The dark semi-solid residue was slowly poured into rapidly stirred
ice water (2 L). A fine, olive-green solid precipitated in the
water. The solid suspension was extracted with ethyl acetate (1 L)
followed by further extractions with ethyl acetate (4.times.400
mL). The organic fractions were combined and dried over anhydrous
magnesium sulfate (250 g). After stirring overnight, the drying
agent was removed by vacuum filtration through a Celite pad. The
ethyl acetate was removed on a rotary evaporator to give a dark
brown-black solid (95 g) that was not further purified. The solid
was dried in a vacuum desiccator overnight at 70.degree. C.
Step 1R. Synthesis of 3',6'-Dichloro-4,5,6,7-tetrafluoran
[0088] Using a mechanical stirrer, tetrafluorofluorescein (95 g,
ca. 0.235 mol) was suspended in a mixture of acetonitrile (350 mL)
and dimethylformamide (5.8 mL). Thionyl chloride (79 mL, 129.3 g,
1.08 mol) was added to this mixture. The reaction mixture was
heated to reflux for 4 hours. HPLC showed complete conversion after
4 hours. The excess acetonitrile and excess thionyl chloride were
removed by distillation in a stream of nitrogen. When nearly all of
the solvent had been removed, the solid was resuspended in a
solution of acetonitrile/water (95:5). The violet-brown solid was
collected by vacuum filtration, washed with 95:5 acetonitrile/water
(500 mL) followed by drying in a vacuum desiccator at 70.degree. C.
for 4 hours to give the desired product (84 g, 0.19 mol, 80%
yield).
Step 1S. Synthesis of
3'-indolino-6'chloro-4,5,6,7-tetrafluorofluoran
[0089] 3',6'-Dichloro-4,5,6,7-tetrafluorofloran (20 g, 0.045 mol),
2,6-lutidine (4.74 g, 0.045 mol) and sulfolane (56 mL) were added
to a 250 mL 3-neck round bottom flask fitted with a mechanical
stirrer. Aluminum chloride (40.2 g, 0.28 mol) was added in small
portions and the resulting mixture was stirred for 20 minutes. The
temperature rose to 110.degree. C. Indoline (5.13 g, 0.045 mol) was
added slowly followed by 2,6-lutidine (4.74 g, 0.045 mol) and the
reaction was heated at 110.degree. C. for 5 hours. The reaction was
followed to completion by HPLC. The reaction was poured into a
mixture of crushed ice and water with vigorous agitation. The dark
blue solid was collected by suction filtration, washed with water
and dried under vacuum. The crude product was passed through a
silica gel plug (300 g) using methylene chloride to elute. Removal
of solvent provided the indolinofluoran as a yellow-green foam (16
g, 0.031 mol, 68% yield). The structure was confirmed by NMR and
mass spectroscopy.
Step 1T. Synthesis of
3'-(5-methylindolino)-6'chloro-4,5,6,7-tetrafluorofluoran
[0090] 3',6'-Dichloro-4,5,6,7-tetrafluorofluoran (13.23 g, 0.030
mol), 2,6-lutidine (6.43 g, 0.060 mol) and sulfolane (30M1) were
added to a 100 mL 3-neck round bottom flask fitted with a
condenser. Aluminum chloride (16 g, 0.120 mol) was added followed
by 5-methylindoline (4.0 g, 0.030 mol) and the reaction was heated
at 110-120.degree. C. for 20 hours under nitrogen. The reaction
mixture was poured into a mixture of crushed ice, water, and
hydrochloric acid (500 mL) with vigorous agitation and stirred for
0.5 hour. The solid was dissolved in ethyl acetate and washed with
10% sodium bicarbonate solution. The organic layer was separated,
dried over sodium sulfate and concentrated The crude product was
passed through a short column of silica gel using methylene
chloride to elute. Removal of solvent provided the
3'-(5-methylindolino)-6'-chloro-4,5,6,7-tetraflourofluoran as a
solid (4.6 g, 8.5 mmol, 28% yield).
[0091] The structure was confirmed by NMR and mass
spectroscopy.
Example II
[0092] Synthesis of Dye I
[0093] A mixture of hexachlorofluoran (2.0 g, 3.9 mmol),
2,3,3-trimethylindoline (0.9 g; 5.9 mmol), zinc chloride (1.6 g;
11.8 mmol), and zinc oxide (0.5 g; 5.9 mol) in sulfolane (6 g) was
stirred with heating at 190.degree. C. for 4 hours. To this mixture
was added aniline (0.8 g; 7.9 mmol) and the mixture was then
further stirred with heating at 160.degree. C. for 14 hours. The
mixture was cooled to 50.degree. C. and quenched into 2N HCl (100
mL). The crude solid was isolated by filtration, washed with water
several times and taken up in methylene chloride (150 mL). The
methylene chloride solution was washed with sat. sodium bicarbonate
(2.times.100 mL), dried over magnesium sulfate and the solvent
removed. The residual solid was purified by column chromatography
on silica gel (eluted with 30% ethyl acetate in hexane) to give 0.6
g pure product (22% yield) and then recrystallized from ca. 10%
acetone in hexane to give colorless crystalline product, m.p.
210-215.degree. C. (0.35 g, 13% yield). The structure was confirmed
by proton NMR and mass spectroscopy.
Example III
[0094] Synthesis of Dye II
[0095] A mixture of hexachlorofluoran (2.0 g, 3.9 mmol), indoline
(0.7 g, 5.9 mmol), zinc chloride (1.6 g, 11.8 mmol), and zinc oxide
(0.5 g, 5.9 mmol) in sulfolane (6 g) was stirred with heating at
145.degree. C. for 90 minutes. To this mixture was added
4-(2-ethyl-1-hexyloxy) aniline (2.7 g, 7.9 mmol) and the mixture
was further stirred with heating at 160.degree. C. for 5 hours. The
mixture was cooled to 50.degree. C. and quenched into 2N HCl (100
mL). The crude solid was isolated by filtration, washed with water
several times and taken up in methylene chloride (150 mL). The
methylene chloride solution was washed with sat. sodium bicarbonate
(2.times.100 mL), dried over magnesium sulfate and the solvent was
evaporated. The residual solid was purified by column
chromatography (10% ethyl acetate in methylene chloride) to give
1.2 g pure product (39% yield) and recrystallized from
approximately 10% acetone/hexane to give colorless crystalline
product (0.55 g, m.p. 180-182.degree. C., 18% yield). The structure
was confirmed by proton NMR and mass spectroscopy.
Example IV
[0096] Synthesis of Dye III
[0097] Pentachloroindolinofluoran (11.8 g, 20 mmol), ZnCl.sub.2
(8.2 g, 60 mmol) and ZnO (2.43 g, 30 mmol) were added to a 250 ml
round bottom flask containing sulfolane (30 g) and the flask warmed
to dissolve the solids. To the hot blue solution was added
3,4-dioctyloxyaniline (13.96 g, 40 mmol) and the flask was placed
with an air condenser into an oil bath preheated to 140.degree. C.
The reaction mixture was stirred at that temperature for 2 hours.
The reaction was followed by TLC (25% ethyl acetate in hexane)
until complete. The reaction mixture was cooled and 2N HCl (400 mL)
was added followed by trituration with a spatula to break the large
blue mass to a crystalline powder. The reaction mixture was
filtered and washed copiously with water. The crude product was
dissolved in ethyl acetate (1200 mL) and extracted with 10%
Na.sub.2CO.sub.3 (2.times.250 mL), followed by water and brine (250
mL each). The organic layer was dried over sodium sulfate and
evaporated to yield crude blue product (23 g). The crude product
was purified on a silica gel column (1.5Kg) packed in methylene
chloride. The product was eluted with 10% ethyl acetate/methylene
chloride (5 L). Pure fractions were pooled to obtain the product as
a glass (13.5 g) which was crystallized from 10% acetone in hexane
to obtain a first crop of colorless crystals (8.5 g, 9.4 mmol, 47%
yield). Recrystallization of the mother liquor provided a second
crop of crystals (2.5 g, 2.7 mmol, 13.5% yield). The overall yield
was 11.0 g, 12.1 mmol, 60.5% yield. NMR analysis and mass
spectroscopy confirmed the structure.
Example V
[0098] Synthesis of Dye IV
[0099] 3'-Indolinopentachlorofluorescin (2.15 g, 3.6 mmol),
4-(2-hydroxy-1-decyloxy)aniline (1,81 g, 6.8 mmol), zinc chloride
(1.5 g, 11 mmol), zinc oxide (0.45 g, 5.6 mmol) and tetramethylene
sulfone (8 g) were added to a 100-mL flask. The reaction mixture
was heated at 150.degree. C. for 12 hours under an atmosphere of
nitrogen. The cooled mixture was poured into 2N hydrochloric acid
(100 mL). A dark blue precipitate was obtained and filtered and
washed with 0.5N aq. hydrochloric acid solution (100 mL) and water
(100 mL). The crude product was purified by silica gel column
chromatography (loaded and eluted with 500 ml of methylene
chloride, followed by 500 ml of 1% methanol/methylene chloride).
The solvent was removed by rotary evaporation to collect a dark
blue powder (2.3 g, 2.77 mmol, 77% yield). Pale greenish crystals
were obtained by recrystallization from 10% acetone/hexanes. m.p:
156-158.degree. C. The structure was confirmed by proton NMR and
mass spectroscopy.
Example VI
[0100] Synthesis of Dye V
[0101] A mixture of hexachlorofluoran (1.0 g, 1.9 mmol),
5-methoxyindoline (0.5 g, 3.0 mmol), zinc chloride (0.8 g, 5.9
mmol), and zinc oxide (0.3 g, 2.5 mmol) in sulfolane (4 g) was
stirred with heating at 145.degree. C. for 2 hours. To this mixture
was added 3, 4-dioctyloxyaniline (1.4 g, 4.0 mmol) and the mixture
was further stirred with heating at 160.degree. C. for 5 hours. The
mixture was cooled to 50.degree. C. and quenched into 2N HCl (100
mL). The crude solid was isolated by filtration, washed with water
several times and taken up in methylene chloride (150 mL). The
methylene chloride solution was washed with sat. sodium bicarbonate
(2 x 100 mL), dried over magnesium sulfate and the solvent was
removed. The residual solid was purified by column chromatography
on silica gel eluted with 20% ethyl acetate in methylene chloride
to give pure product (0.80 g, 0.836 mmol, 44% yield) which was
recrystallized from acetonitrile to give colorless crystalline
product (0.35 g, 0.836 mmol, 19% yield) m.p. 117-119.degree. C. The
structure was confirmed by proton NMR and mass spectroscopy.
Example VII
[0102] Synthesis of Dye VI
[0103] A mixture of 3'-indolino-6'-chloro-4,5,6,7-tetrafluorofloran
(1.0 g, 1.9 mmol), zinc chloride (0.8 g, 5.7 mmol), zinc oxide (0.2
g, 2.8 mmol), and 2-isopropylanilne (0.5 g, 3.8 mmol) in sulfolane
(4 g) was stirred with heating at 160.degree. C. for 14 hours. The
mixture was cooled to 50.degree. C. and quenched into 2N HCl (100
mL). The crude solid was isolated by filtration, washed with water
several times and taken up in methylene chloride (150 mL). This
methylene chloride solution was washed with sat. sodium bicarbonate
(2 x 100 mL), and dried over magnesium sulfate to remove the
solvent. The residual solid was purified by column chromatography
on silica gel eluted with 35% ethyl acetate in methylene chloride
to give pure product (0.60 g, 0.95 mmol, 50% yield) which was
recrystallized from 10% acetone in hexane to give colorless
crystalline product (0.3 g, 0.475 mmol, 25% yield) m.p.
209-210.degree. C. The structure was confirmed by proton NMR and
mass spectroscopy.
Example VIII
[0104] Synthesis of Dye VII
[0105] A mixture of
3'-indolino-6'-chloro-4,5,6,7-tetrafluorofluoran (7.80 g, 15 mmol),
zinc chloride (6.13 g, 45 mmol), zinc oxide (1.22 g, 15 mmol), and
2-methyl-4-decyloxyaniline (7.89 g, 30 mmol) in sulfolane (30 g)
was stirred with heating at 160-170.degree. C. for 24 hours.
Analysis by TLC (30% ethyl acetate/methylene chloride) showed a
major product at Rf=0.5 with a mass spectrum consistent with the
product (M+1=751). The reaction mixture was poured onto a mixture
of ice/water/hydrochloric acid, stirred for 1/2 hour, filtered and
dried. The crude product was dissolved in ethyl acetate (700 mL)
and stirred for one hour with 10% sodium bicarbonate solution (300
mL). After filtration through a pad of Celite the organic layer was
separated, dried over sodium sulfate and concentrated to a thick
oil. Column chromatography on silica gel (400 g, 10-30% ethyl
acetate/methylene chloride) provided pure fractions which were
concentrated and recrystallized from acetone/hexane to yield
colorless crystals (5.85 g), m.p. 137-139.degree. C. A second crop
(1.0 g) was obtained to give a total of 6.85 g (9.12 mmol, 61%
yield). The structure was confirmed by NMR and mass
spectroscopy.
Example IX
[0106] Synthesis of Dye VIII
[0107] A mixture of
3'-(5-methylindolino)-6'-chloro-4,5,6,7-tetrafluorofluoran (1.343
g, 2.5 mmol), zinc chloride (1.022 g, 7.5 mmol), zinc oxide (0.203
g, 2.5 mmol), and 2-methyl-4-decyloxyaniline (1.375 g, 5 mmol) in
sulfolane (5 g) was stirred with heating at 160-175.degree. C. for
24 hours. The reaction mixture was poured onto a mixture of
ice/water/hydrochloric acid, stirred for 1/2 hour, filtered and
dried. The crude product was dissolved in methylene chloride,
treated with triethylamine (7 mL) and evaporated. Column
chromatography on silica gel (250 mL, 50% ethyl acetate/methylene
chloride) provided pure fractions which were concentrated and
recrystallized from acetone/hexane to yield colorless crystals
(0.700 g, 0.915 mmol, 37% yield) m.p. 170-171.5.degree. C. The
structure was confirmed by NMR and mass spectroscopy.
Example X
[0108] Synthesis of Dye IX
[0109] A mixture of
3'-indolino-6'-chloro-4,5,6,7-tetrafluorofluoran (1.0 g, 1.9 mmol),
zinc chloride (0.8 g, 5.7 mmol), zinc oxide (0.2 g, 2.8 mmol), and
2-methyl-4-octadecyloxyanilne (1.4 g, 3.8 mmol) in sulfolane (4 g)
was stirred with heating at 160.degree. C. for 14 hours. The
mixture was cooled to 50.degree. C. and quenched into 2N HCl (100
mL). The crude solid was isolated by filtration, washed with water
several times and taken up in methylene chloride (150 mL). This
methylene chloride solution was washed with sat. sodium bicarbonate
(2.times.100 mL) and dried over magnesium sulfate to remove the the
solvent. The residual solid was purified by column chromatography
on silica gel eluted with 35% ethyl acetate in methylene chloride
to give pure product (1.0 g, 116 mmol, 61% yield) which was
recrystallized from 10% acetone in hexane to give colorless
crystalline product (0.5 g, 0.57 mmol, 30% yield); m.p.
136-138.degree. C.). The structure was confirmed by NMR and mass
spectroscopy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0110] FIG. 1 is a schematic, side sectional view of a three-color
thermal imaging member according to the invention.
SUMMARY OF THE INVENTION
[0111] It is an object of this invention to provide novel thermal
imaging members and methods.
[0112] Another object of the invention is to provide thermal
imaging members and methods that utilize a color-former that
exhibits different colors when in a crystalline form than when in
an amorphous form.
[0113] Yet another object of the invention is to provide imaging
members and methods that utilize certain rhodamine
color-formers.
[0114] According to one aspect of the invention there are provided
novel thermal imaging members and methods that utilize certain
rhodamine color-forming compounds that exhibit a first color when
in a crystalline form and a second color, different from the first
color, when in an amorphous form.
[0115] In one embodiment of the invention there are provided novel
thermal imaging members and methods that utilize compounds that are
represented by formula I:
##STR00002##
wherein:
[0116] R.sub.1, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are
each independently selected from the group consisting of hydrogen,
alkyl, preferably having from 1 to 18 carbon atoms, substituted
alkyl, alkenyl, substituted alkenyl, alkynyl, substituted, alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, acylamino, halogen, nitro, nitrilo, sulfonyl, aryl,
substituted aryl, heteroaryl, substituted heteroaryl, oxygen,
substituted oxygen, nitrogen, substituted nitrogen, sulfur and
substituted sulfur;
[0117] R.sub.2 is selected from the group consisting of hydrogen,
alkyl, preferably having from 1 to 18 carbon atoms, substituted
alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, sulfonyl, aryl, substituted aryl, heteroaryl, substituted
heteroaryl, substituted oxygen, substituted nitrogen and
substituted sulfur;
[0118] R.sub.8 is absent or selected from the group consisting of
hydrogen, alkyl, preferably having from 1 to 18 carbon atoms,
substituted alkyl, alkenyl, substituted alkenyl, alkynyl,
substituted alkynyl, heterocycloalkyl, substituted
heterocycloalkyl, substituted carbonyl, acylamino, halogen, nitro,
nitrilo, sulfonyl, aryl, substituted aryl, heteroaryl, substituted
heteroaryl, oxygen, substituted oxygen, nitrogen, substituted
nitrogen, sulfur and substituted sulfur;
[0119] R.sub.9, R.sub.10 and R.sub.11 are independently selected
from the group consisting of hydrogen, alkyl, preferably having
from 1 to 18 carbon atoms, substituted alkyl, alkenyl, substituted
alkenyl, alkynyl, substituted alkynyl, heterocycloalkyl,
substituted heterocycloalkyl, substituted carbonyl, acylamino,
halogen, nitro, nitrilo, sulfonyl, aryl, substituted aryl,
heteroaryl, substituted heteroaryl, oxygen, substituted oxygen,
nitrogen, substituted nitrogen, sulfur and substituted sulfur;
[0120] R.sub.12, R.sub.13, R.sub.14 and R.sub.15 are independently
selected from the group consisting of hydrogen, alkyl, preferably
having from 1 to 18 carbon atoms, substituted alkyl, alkenyl,
substituted alkenyl, alkynyl, substituted alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, acylamino, aryl, substituted aryl, heteroaryl, and
substituted heteroaryl;
[0121] R.sub.16, R.sub.17, R.sub.18 and R.sub.19 are independently
selected from the group consisting of hydrogen, alkyl, preferably
having from 1 to 18 carbon atoms, substituted alkyl, alkenyl,
substituted alkenyl, alkynyl, substituted alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, acylamino, halogen, nitro, nitrilo, sulfonyl, aryl,
substituted aryl, heteroaryl, substituted heteroaryl, oxygen,
substituted oxygen, nitrogen, substituted nitrogen, sulfur and
substituted sulfur; and
[0122] X.sub.1 is carbon or nitrogen; wherein the compound of
formula I is in the crystalline form.
[0123] Preferred thermal imaging members and methods of the present
invention comprise a compound represented by formula I in which
R.sub.8, R.sub.9, R.sub.10 and R.sub.11 are fluorine, R.sub.12 and
R.sub.13 are hydrogen atoms, R.sub.14 and R.sub.15 are identical
alkyl groups, preferably methyl groups, R.sub.1, R.sub.2, R.sub.3,
R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.16, R.sub.17, R.sub.18
and R.sub.19 are as previously defined and X.sub.1 is carbon.
[0124] In another aspect of the present invention there are
provided compounds of formula I in which:
[0125] R.sub.1, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are
each independently selected from the group consisting of hydrogen,
alkyl, preferably having from 1 to 18 carbon atoms, substituted
alkyl, alkenyl, substituted alkenyl, alkynyl, substituted, alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, acylamino, halogen, nitro, nitrilo, sulfonyl, aryl,
substituted aryl, heteroaryl, substituted heteroaryl, oxygen,
substituted oxygen, nitrogen, substituted nitrogen, sulfur and
substituted sulfur;
[0126] R.sub.2 is selected from the group consisting of aryl and
substituted aryl;
[0127] R.sub.8, R.sub.9, R.sub.10 and R.sub.11 are fluorine;
R.sub.12 and R.sub.13 are hydrogen atoms;
[0128] R.sub.14 and R.sub.15 are identical substituents selected
from the group consisting of alkyl having from 1 to 18 carbon atoms
and substituted alkyl having from 1 to 18 carbon atoms;
[0129] R.sub.16, R.sub.17, R.sub.18 and R.sub.19 are independently
selected from the group consisting of hydrogen, alkyl, preferably
having from 1 to 18 carbon atoms, substituted alkyl, alkenyl,
substituted alkenyl, alkynyl, substituted alkynyl,
heterocycloalkyl, substituted heterocycloalkyl, substituted
carbonyl, acylamino, halogen, nitro, nitrilo, sulfonyl, aryl,
substituted aryl, heteroaryl, substituted heteroaryl, oxygen,
substituted oxygen, nitrogen, substituted nitrogen, sulfur and
substituted sulfur; and
[0130] X.sub.1 is carbon.
[0131] In yet another aspect of the present invention there is
provided a compound of formula I in which R.sub.2 is a
2,4-dimethylphenyl group, R.sub.8, R.sub.9, R.sub.10 and R.sub.11
are fluorine, R.sub.14, R.sub.15 and R.sub.17 are methyl groups,
R.sub.1, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.12,
R.sub.13, R.sub.16, R.sub.18 and R.sub.19 are hydrogen and
X.sub.1is carbon, i.e.,
3'-(3,3,5-trimethylindolino)-6'-(2,4-dimethylanilino)-4,5,6,7-tetrafluoro-
fluoran.
DETAILED DESCRIPTION
[0132] According to the present invention, the compounds of formula
I may be incorporated into any thermal imaging members and used in
any thermal imaging methods, including direct thermal imaging
members and thermal transfer imaging members and methods.
[0133] Preferred thermal imaging members according to the invention
are direct thermal imaging members, particularly those having the
structures described in U.S. Pat. No. 6,801,233 B2 and U.S. patent
application Ser. No. 11/400735, filed Apr. 6, 2006.
[0134] Other preferred thermal imaging members are those for use in
thermal transfer imaging methods, particularly those having the
structures described in U.S. Pat. No. 6,537,410.
[0135] Further preferred thermal imaging members are thermal
transfer imaging members having the structures described in
commonly assigned U.S. Pat. No. 6,054,246.
[0136] Direct thermal imaging members according to the invention,
for use in direct thermal printing methods, include all the
color-forming reagents necessary to form an image in the member
itself. Direct thermal imaging members according to the invention
generally comprise a substrate carrying at least one image-forming
layer that includes a compound according to formula I in the
crystalline form. The crystalline form of a compound of formula I
can be converted at least partially to an amorphous form, the
amorphous form having intrinsically a different color from the
crystalline form. The imaging member may be monochromatic, in which
an image-forming layer includes at least one compound of formula I,
or polychromatic. Multicolor direct thermal imaging members include
at least two, and preferably three, image-forming layers, and the
temperature at which an image is formed in at least one of the
image-forming layers is preferably time-interval-independent.
Preferred imaging members according to the invention are direct
multicolor thermal imaging members.
[0137] The conversion from the crystalline form to the amorphous
form in accordance with the thermal imaging members and thermal
imaging methods of the invention is carried out by applying heat to
compositions comprising the compounds of formula I. In the thermal
imaging methods of the invention, heat may be applied to the
thermal imaging members that contain compositions comprising the
compounds of formula I by any of the techniques known in thermal
imaging such as from a thermal print head, a laser, a heated
stylus, etc.
[0138] In one embodiment of the present invention, one or more
thermal solvents, which are crystalline materials, can be
incorporated in the thermal imaging member. The crystalline thermal
solvent(s), upon being heated, melt and thereafter dissolve or
liquefy the crystalline color-forming material of formula I,
thereby converting it to the amorphous form and providing a color
change (i.e., an image). Thermal solvents may be advantageously
used when it is required for a color-forming layer in a direct
thermal imaging member to have an activation temperature (the
temperature at which color is formed or at which color changes)
that is lower than the melting point of the compound of formula I.
The melting point of the thermal solvent, rather than that of the
compound of formula I, may in such a case establish the activation
temperature of a color-forming layer.
[0139] It will be clear to one of ordinary skill in the art that
the activation temperature of a color-forming layer that comprises
a mixture of crystalline materials may be different from the
melting points of any of the individual components. A eutectic
mixture of two crystalline components, for example, melts at a
lower temperature than either of the components in isolation.
Conversely, if the rate of solubilization of the compound of
formula I in the molten thermal solvent is slow, the activation
temperature of the mixture may be higher than the melting point of
the thermal solvent. Recall that the activation temperature of a
mixture of a compound of formula I and a thermal solvent is the
temperature at which the color of the mixture changes, i.e., the
temperature at which a sufficient amount of the compound of formula
I dissolves in the molten thermal solvent to provide a visible
color change. It will be clear from the above discussion that the
activation temperatures of mixtures of compounds of formula I and
thermal solvents may be dependent upon the rate of heating. For
these reasons, in the design of thermal imaging members of the
present invention determination of the actual activation
temperature of a composition is preferred to be carried out
experimentally.
[0140] Any suitable thermal solvents may be incorporated in the
thermal imaging members of the invention. Suitable thermal solvents
include, for example, aromatic and aliphatic ethers, diethers and
polyethers, alkanols containing at least about 12 carbon atoms,
alkanediols containing at least about 12 carbon atoms,
monocarboxylic acids containing at least about 12 carbon atoms,
esters and amides of such acids, aryl amides, especially
benzanilides, aryl sulfonamides and hydroxyalkyl-substituted
arenes.
[0141] Specific preferred thermal solvents include:
1,2-diphenoxyethane, 1,2-bis(4-methylphenoxy)ethane,
tetradecan-1-ol, hexadecan-1-ol, octadecan-1-ol, dodecane-1,2-diol,
hexadecane-1,16-diol, myristic acid, palmitic acid, stearic acid,
methyl docosanoate, 1,4-bis(hydroxymethyl)benzene, and
p-toluenesulfonamide.
[0142] Particularly preferred thermal solvents are diaryl sulfones
such as diphenylsulfone, 4,4'-dimethyldiphenylsulfone, phenyl
p-tolylsulfone and 4, 4'-dichlorodiphenylsulfone, and ethers such
as 1,2-bis(2,4-dimethylphenoxy)ethane,
1,4-bis(4-methylphenoxymethyl)benzene and
1,4-bis(benzyloxy)benzene.
[0143] When converted to the colored form the compounds of formula
I (in the closed form) have the open form illustrated by formula
II:
##STR00003##
wherein R.sub.1-R.sub.19 and X.sub.1 are as defined above with
respect to formula I.
[0144] It is possible that the dissolution of the compounds of
formula I by a thermal solvent may lead to an amorphous form (in
which the compound is dissolved in the amorphous thermal solvent)
in which the proportion of the open, colored form is different from
the proportion that would be present in the amorphous form
resulting from melting the compound of formula I alone (i.e.,
without interaction with the thermal solvent). In particular, the
proportion of the open, colored form of the compound in the
amorphous material may be enhanced by use of hydrogen-bonding or
acidic thermal solvents. Materials that increase the proportion of
the color-forming material that is in the open, colored form are
hereinafter referred to as "developers". It is possible that the
same compound may serve the function of thermal solvent and
developer. Preferred developers include phenols such as
2,2'-methylenebis(6-tert-butyl-4-methylphenol),
2,2'-methylenebis(6-tert-butyl-4-ethylphenol),
2,2'-ethylidenebis(4,6-di-tert-butylphenol),
bis[2-hydroxy-5-methyl-3-(1-methylcyclohexyl)phenyl]methane,
1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate,
2,6-bis[[3-(1,1-dimethylethyl)-2-hydroxy-5-methylphenyl]methyl]-4-methylp-
henol, 2,2'-butylidenebis[6-(1,1-dimethylethyl)-4-methylphenol,
2,2'-(3,5,5-trimethylhexylidene)bis[4,6-dimethyl-phenol],
2,2'-methylenebis[4,6-bis(1,1-dimethylethyl)-phenol,
2,2'-(2-methylpropylidene)bis[4,6-dimethyl-phenol],
1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane,
tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate,
2,2'-thiobis(4-tert-octylphenol), and
3-tert-butyl-4-hydroxy-5-methylphenyl sulfide.
[0145] In order for the image formed by the amorphous color-former
to be stable against recrystallization back to the crystalline
form, preferably the glass transition temperature (T.sub.g) of the
amorphous mixture of the color-former and any thermal solvent
should be higher than any temperature that the final image must
survive. Typically, it is preferred that the T.sub.g of the
amorphous, colored material be at least about 50.degree. C., and
ideally above about 60.degree. C. In order to ensure that the
T.sub.g is sufficiently high for a stable image to be formed,
materials having a high T.sub.g may be added to the color-forming
composition. Such materials, hereinafter referred to as
"stabilizers", when dissolved in the amorphous mixture of
color-former, optional thermal solvent, and optional developer,
serve to increase the thermal stability of the image.
[0146] Preferred stabilizers have a T.sub.g that is at least about
60.degree. C., and preferably above about 80.degree. C. Examples of
such stabilizers are the aforementioned
1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate
(T.sub.g 123.degree. C.) and
1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane (T.sub.g
101.degree. C.). The stabilizer molecule may also serve as a
thermal solvent or as a developer.
[0147] For example, the color-forming material may itself have a
melting temperature above the desired temperature for imaging, and
a T.sub.g (in the amorphous form) of about 60.degree. C. In order
to produce a color-forming composition melting a the desired
temperature, it may be combined with a thermal solvent (for
example, a diaryl sulfone) that melts at the desired temperature
for imaging. The combination of thermal solvent and color-forming
material may, however, have a T.sub.g that is substantially lower
than 60.degree. C., rendering the (amorphous) image unstable. In
this case, a stabilizer such as
1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate
may be added, to raise the T.sub.g of the amorphous material. In
addition, there may be provided a developer, for example, a
phenolic compound such as
2,2'-ethylidenebis(4,6-di-tert-butylphenol), in order to increase
the proportion of the color-forming material that is in the colored
form in the amorphous phase.
[0148] Preferably the color-forming compound of the present
invention, the (optional) thermal solvent, the (optional) developer
and the (optional) stabilizer are each predominantly in their
crystalline forms prior to imaging. By "predominantly" is meant at
least about 50%). During imaging, at least one of these materials
melts and an amorphous mixture of the materials is formed. The
amorphous mixture is colored, whereas the crystalline starting
materials are not.
[0149] It is possible that one of the components in the amorphous,
colored mixture may recrystallize after the image has been formed.
It is desirable that such recrystallization not change the color of
the image. In the case that a color-former, thermal solvent,
developer and stabilizer are used, the thermal solvent may
typically recrystallize without greatly affecting the color of the
image.
[0150] The substituents on the compounds of formula I are
preferably chosen to minimize the water solubility of the compounds
and facilitate the formation of a colorless form in non-polar,
non-protic solvents. This is because the manufacture of a thermal
imaging member of the present invention typically involves an
aqueous coating process. Were the compound of formula I to dissolve
appreciably in water (the coating solvent), the coloration that is
intended to occur when heating the thermal imaging member itself
would occur prematurely during manufacture. On the other hand, the
thermal solvents, when used, are typically non-polar, non-protic
solvents, and are intended to dissolve the compounds of formula
I.
[0151] Another consideration that influences the choice of
substituents on the compounds of formula I is the color provided by
the open form, namely formula II. Compounds of formula II (in the
open form) typically exhibit maximum absorption of light in the
range of 600-700 nm. As such, these compounds are typically cyan
dyes. As discussed above, the quality of the cyan chromophore is
typically optimized when substituents R.sub.8-R.sub.11 are
electron-withdrawing relative to hydrogen, and X.sub.1 is carbon.
In dyes I-V described above, substituents R.sub.8-R.sub.11 are
chlorine atoms, while in dyes VI-IX substituents R.sub.8-R.sub.11
are fluorine atoms.
[0152] Yet another consideration is the stability of the image
formed by the compound of formula I. When used in a direct thermal
imaging member, the colorless form of the compound (formula I
itself) and the colored form of the compound (formula II) each must
be stable, since in such imaging members the material is present
both in colored and uncolored regions. In particular, the forms
represented by formulas I and II must be stable to ultraviolet
light and to oxidation in the presence or absence of light of any
wavelength. The present inventors have found that the colored form
(formula II) of dyes such as dyes I-V, in which substituents
R.sub.8-R.sub.11 are chlorine atoms, may be prone to darkening to
an almost black color in the presence of light and oxygen, whereas
the colored form of dyes such as VI-IX, in which substituents
R.sub.8-R.sub.11 are fluorine atoms, is much more stable under
these conditions.
[0153] As used in thermal imaging members of the present invention,
the colorless form of compounds is, as noted above, present in the
crystalline state. The stability of the colorless form in the
crystalline state may be compromised if any reactions, particularly
photochemical reactions, occur within or at the surface of crystals
of the compounds. As noted above, it is preferred (for optimization
of the chromophore) that substituents R.sub.8-R.sub.11 be
electron-withdrawing relative to hydrogen, preferably halogen
substituents. The resulting highly substituted phenyl substituent
then becomes, however, an excellent electron acceptor that can
participate in electron transfer reactions with electron donating
groups. Such reactions can be facilitated by the absorption of
light, particularly light of short wavelengths.
[0154] Those of ordinary skill in the art will notice that the
compounds of formula I, in the non-colored form, comprise
electron-donating portions (the indoline and amino substituents)
and, as noted, electron-accepting portions (the lower benzene ring
when substituted with four halogen atoms). The present inventors
have found that certain compounds of formula I can self-oxidize in
the crystalline form, in the presence of light of ultraviolet and
short blue wavelengths. This reaction causes the colorless crystals
of such compounds to darken. When the darkened crystals are
analyzed, it is found that a common product involves oxidation of
the indoline portion of the molecule to an indole.
[0155] This reaction, being an oxidation, involves loss of a
hydrogen atom from one of positions R.sub.12 and R.sub.13 and one
of positions R.sub.14 and R.sub.15. Therefore, its occurrence can
be prevented if neither of R.sub.12 and R.sub.13 is a hydrogen
atom, and/or neither R.sub.14 and R.sub.15 of is a hydrogen atom.
The synthesis of compounds of formula I in which substituents
R.sub.14 and R.sub.15 are other than hydrogen is more
straightforward than the alternative in which substituents R.sub.12
and R.sub.13 are other than hydrogen, as will be clear to one of
ordinary skill in the art. The present inventors have found that
undesirable coloration of the colorless, crystalline form of
compounds of the present invention in the presence of light is
greatly reduced when substituents R.sub.14 and R.sub.15 are both
alkyl groups, preferably methyl groups.
[0156] In compound I, above, the three groups R.sub.13, R.sub.14
and R.sub.15 are methyl groups. However, as will be clear to one of
ordinary skill in the art, in this case there become two chiral
centers in the compound: that at the carbon atom that bears the
R.sub.13 substituent, and that at the spiro center of the lactone
ring. The presence of two chiral centers means that the compound
can exist as two diastereoisomers, which having different shapes
from each other may not pack easily into a crystalline form. It is
preferred, for ease of crystallization, that diastereoisomeric
mixtures not be used in the practice of the present invention.
[0157] For this reason, it is preferred that substituents R.sub.12
and R.sub.13 both be hydrogen atoms, and substituents R.sub.14 and
R.sub.15 both be identical alkyl groups, preferably methyl
groups.
[0158] A particularly preferred compound of formula I in which
substituents R.sub.8-R.sub.11 are fluorine atoms, substituents
R.sub.12 and R.sub.13 are both hydrogen atoms, and substituents
R.sub.14 and R.sub.15 are both methyl groups is dye X,
3'-(3,3,5-trimethylindolino)-6'-(2,4-dimethylanilino)-4,5,6,7-tetrafluoro-
fluoran.
[0159] The compounds used according to the invention may be
prepared by synthetic processes which are known to those skilled in
the art, particularly in view of the state of the art in organic
synthetic processes, and the present disclosure and specific
preparatory examples provided below herein.
[0160] Generally, symmetrical rhodamine dyes can be prepared in one
step from 3',6'-dichlorofluorans by reacting two equivalents of an
aromatic or aliphatic amine as described in U.S. Pat. 4,602,263,
GB2311075 and DE81056. The unsymmetrical rhodamine dyes are then
prepared by the selective monoalkylation of symmetrical rhodamines
using sodium hydride in dimethyl sulfoxide as described in U.S.
Pat. Nos. 4,602,263 and 4,826,976.
[0161] Alternatively, the unsymmetrical rhodamines can be prepared
by use of an alternate synthetic pathway in which one equivalent of
an N-alkylaniline is reacted selectively with the
3',6'-dichlorofluoran using aluminum chloride as a catalyst to
produce 3'-chloro-6'-N-alkyl-N-arylfluorans. These products are
isolated and purified prior to reacting with a second equivalent of
an aromatic or aliphatic amine. Zinc chloride is used as the
catalyst for the second addition. DE139727 describes the selective
addition of anilines to 3',6'-dichlorofluorans to produce
3'-chloro-6'-arylaminofluorans using a mixture of zinc chloride and
zinc oxide at 160.degree. C.
[0162] Unsymmetrical rhodamines can also be made from 2-benzoyl
benzoic acid derivatives by condensation with 3-arylamino phenols
or 3-alkylamino phenols as described in Chemistry and Applications
of Leuco Dyes, pp. 180-191 R. Muthyala, Ed., Plenum Press, New York
and London, 1997 and also U.S. Pat. Nos. 4,390,616 and
4,436,920.
[0163] The 3',6'-dichlorofluorans are synthesized from the
corresponding fluoresceins using thionyl chloride and
dimethylformamide in a variation of the method of Hurd described in
the Journal of the Amer. Chemical Soc. 59, 112 (1937).
[0164] Careful recrystallization from solvent mixtures such as
hexanes/acetone or hexanes/ethyl acetate produces colorless
crystalline material which is preferred for use in thermal imaging
members.
[0165] An example of the preparation of a preferred compound of the
present invention, dye X, is given below.
[0166] One preferred thermal imaging member according to the
present invention is constructed as follows.
[0167] The substrate is a filled, white poly(ethylene
terephthalate) base of thickness about 75 microns, Melinex 339,
available from Dupont Teijin Films, Hopewell, Va.
[0168] A first layer deposited on the substrate is an optional
oxygen barrier layer composed of a fully hydrolyzed poly(vinyl
alcohol), for example, Celvol 325, available from Celanese, Dallas,
Tex. (96.7% by weight), glyoxal (a crosslinker, 3% by weight) and
Zonyl FSN (a coating aid, available from Dupont, Wilmington, Del.,
0.3% by weight). This layer, when present, has a coverage of about
1.0 g/m.sup.2.
[0169] Deposited either directly onto the substrate, or onto the
optional oxygen barrier layer, is a cyan color-forming layer
composed of a cyan color-former, dye X of the present invention,
having melting point 210.degree. C., (1 part by weight), diphenyl
sulfone (a thermal solvent having melting point 125.degree. C.,
coated as an aqueous dispersion of crystals having average particle
size under 1 micron, 3.4 parts by weight), Lowinox WSP (a phenolic
antioxidant, available from Great Lakes Chemical Co., West
Lafayette, Ind., coated as an aqueous dispersion of crystals having
average particle size under 1 micron, 0.75 parts by weight), Chinox
1790 (a second phenolic antioxidant, available from Chitec
Chemical, Taiwan, coated as an aqueous dispersion of crystals
having average particle size under 1 micron, 1 part by weight),
poly(vinyl alcohol) (a binder, Celvol 205, available from Celanese,
Dallas, Tex., 2.7 parts by weight), glyoxal (0.084 parts by weight)
and Zonyl FSN (0.048 parts by weight). This layer has a coverage of
about 2.5 g/m.sup.2.
[0170] Deposited onto the cyan color-forming layer is a barrier
layer that contains a fluorescent brightener. This layer is
composed of a fully hydrolyzed poly(vinyl alcohol), for example,
the abovementioned Celvol 325, available from Celanese, Dallas,
Tex. (3.75 parts by weight), glyoxal (0.08 parts by weight),
Leucophor BCF P115 (a fluorescent brightener, available from
Clariant Corp., Charlotte, N.C., 0.5 parts by weight), boric acid
(0.38 parts by weight) and Zonyl FSN (0.05 parts by weight). This
layer has a coverage of about 1.5 g/m.sup.2.
[0171] The fluorescent brightener serves the purpose in the present
invention of absorbing short wavelength blue and ultraviolet light
that might lead to instability of the crystalline form of the
compound of the present invention that is present in the cyan
color-forming layer. The absorbed light is re-emitted by
fluorescence at a slightly longer wavelength, and thus the short
blue absorbance does not lend a yellow color to the thermal imaging
member. This would not be the case if a conventional absorber of
short blue wavelengths were used.
[0172] Deposited on the barrier layer is a thermally-insulating
interlayer composed of Glascol C-44 (a latex available from Ciba
Specialty Chemicals Corporation, Tarrytown, N.Y., 18 parts by
weight), Joncryl 1601 (a latex available from Johnson Polymer,
Sturtevant, Wis., 12 parts by weight) and Zonyl FSN (0.02 parts by
weight). This layer has a coverage of about 13 g/m.sup.2.
[0173] Deposited on the thermally-insulating interlayer is a
barrier layer composed of a fully hydrolyzed poly(vinyl alcohol),
for example, the abovementioned Celvol 325, available from
Celanese, Dallas, Tex. (2.47 parts by weight), glyoxal (0.07 parts
by weight), boric acid (0.25 parts by weight) and Zonyl FSN (0.06
parts by weight). This layer has a coverage of about 1.0
g/m.sup.2.
[0174] Deposited on the barrier layer is a magenta color-forming
layer, composed of a magenta color-former, Dye IV described in U.S.
patent application Ser. No. 11/433808, filed May 12, 2006, having a
melting point of 152.degree. C.; a phenolic antioxidant (Anox 29,
having melting point 161-164.degree. C., available from Great Lakes
Chemical Co., West Lafayette, Ind., coated as an aqueous dispersion
of crystals having average particle size under 1 micron, 3.58 parts
by weight), Lowinox CA22 (a second phenolic antioxidant, available
from Great Lakes Chemical Co., West Lafayette, Ind., coated as an
aqueous dispersion of crystals having average particle size under 1
micron, 0.72 parts by weight), poly(vinyl alcohol) (a binder,
Celvol 205, available from Celanese, Dallas, Tex., 2 parts by
weight), the potassium salt of Carboset 325 (an acrylic copolymer,
available from Noveon, Cleveland, Ohio, 1 part by weight) glyoxal
(0.06 parts by weight) and Zonyl FSN (0.06 parts by weight). This
layer has a coverage of about 2.7 g/m.sup.2.
[0175] Deposited on the magenta color-forming layer is a barrier
layer composed of a fully hydrolyzed poly(vinyl alcohol), for
example, the abovementioned Celvol 325, available from Celanese,
Dallas, Tex. (2.47 parts by weight), glyoxal (0.07 parts by
weight), boric acid (0.25 parts by weight) and Zonyl FSN (0.06
parts by weight). This layer has a coverage of about 1.0
g/m.sup.2.
[0176] Deposited on the barrier layer is a second
thermally-insulating interlayer composed of Glascol C-44 (1 part by
weight), Joncryl 1601 (a latex available from Johnson Polymer, 0.67
parts by weight) and Zonyl FSN (0.004 parts by weight). This layer
has a coverage of about 2.5 g/m.sup.2.
[0177] Deposited on the second interlayer is a barrier layer
composed of a fully hydrolyzed poly(vinyl alcohol), for example,
the abovementioned Celvol 325, available from Celanese, Dallas,
Tex. (1 part by weight), glyoxal (0.03 parts by weight), boric acid
(0.1 parts by weight) and Zonyl FSN (0.037 parts by weight). This
layer has a coverage of about 0.5 g/m.sup.2.
[0178] Deposited on the barrier layer is a yellow color-forming
layer composed of Dye XI (having melting point 202-203.degree. C.)
described in U.S. Pat. No. 7,279,264 (4.57 parts by weight),
poly(vinyl alcohol) (a binder, Celvol 540, available from Celanese,
Dallas, Tex., 1.98 parts by weight), a colloidal silica (Snowtex
0-40, available from Nissan Chemical Industries, Ltd Tokoyo, Japan,
0.1 parts by weight), glyoxal (0.06 parts by weight) and Zonyl FSN
(0.017 parts by weight). This layer has a coverage of about 1.6
g/m.sup.2.
[0179] Deposited on the yellow color-forming layer is a barrier
layer composed of a fully hydrolyzed poly(vinyl alcohol), for
example, the abovementioned Celvol 325, available from Celanese,
Dallas, Tex. (1 part by weight), glyoxal (0.03 parts by weight),
boric acid (0.1 parts by weight) and Zonyl FSN (0.037 parts by
weight). This layer has a coverage of about 0.5 g/m.sup.2.
[0180] Deposited on the barrier layer is an ultra-violet blocking
layer composed of a nanoparticulate grade of titanium dioxide
(MS-7, available from Kobo Products Inc., South Plainfield, N.J., 1
part by weight), poly(vinyl alcohol) (a binder, Elvanol 40-16,
available from DuPont, Wilmington, Del., 0.4 parts by weight),
Curesan 199 (a crosslinker, available from BASF Corp., Appleton,
Wis., 0.16 parts by weight) and Zonyl FSN (0.027 parts by weight).
This layer has a coverage of about 1.56 g/m.sup.2.
[0181] Deposited on the ultra-violet blocking layer is an overcoat
composed of a latex (XK-101, available from NeoResins, Inc.,
Wilmingtom, Mass., 1 part by weight), a styrene/maleic acid
copolymer (SMA 17352H, available from Sartomer Company, Wilmington,
Pa., 0.17 parts by weight), a crosslinker (Bayhydur VPLS 2336,
available from BayerMaterialScience, Pittsburgh, Pa., 1 part by
weight), zinc stearate (Hidorin F-115P, available from Cytech
Products Inc., Elizabethtown, Ky., 0.66 parts by weight) and Zonyl
FSN (0.04 parts by weight). This layer has a coverage of about 0.75
g/m.sup.2.
[0182] Representative conditions for printing a yellow image using
this preferred thermal imaging member described above are as
follows. [0183] Thermal printing head parameters: [0184] Pixels per
inch: 300 [0185] Resistor size: 2.times.(31.5.times.120) microns
(split resistor) [0186] Resistance: 3000 Ohm [0187] Glaze
Thickness: 110 microns [0188] Pressure: 3 lb/linear inch [0189] Dot
pattern: Slanted grid.
[0190] The yellow color-forming layer is printed as shown in the
table below. The line cycle time is divided into individual pulses
of 75% duty cycle. The thermal imaging member is preheated by
contact with the thermal printing head glaze at the heat sink
temperature over a distance of about 0.3 mm.
TABLE-US-00002 Yellow printing Heat sink 25.degree. C. temperature
Dpi 300 (transport direction) Voltage 38 Line speed 6 inch/sec
Pulse 12.5 microsec interval # pulses used 8-17
[0191] Representative conditions for printing a magenta image using
this preferred thermal imaging member described above are as
follows. Thermal printing head parameters: [0192] Pixels per inch:
300 [0193] Resistor size: 2.times.(31.5.times.120) microns (split
resistor) [0194] Resistance: 3000 Ohm [0195] Glaze Thickness: 200
microns [0196] Pressure: 3 lb/linear inch [0197] Dot pattern:
Slanted grid.
[0198] The magenta color-forming layer is printed as shown in the
table below. The line cycle time is divided into individual pulses
of 7.14% duty cycle. The thermal imaging member is preheated by
contact with the thermal printing head glaze at the heat sink
temperature over a distance of about 0.3 mm.
TABLE-US-00003 Magenta printing Heat sink 30.degree. C. temperature
Dpi 300 (transport direction) Voltage 38 Line speed 0.75 inch/sec
Pulse 131 microsec interval # pulses used 20-30
[0199] Representative conditions for printing a cyan image using
this preferred thermal imaging member described above are as
follows. Thermal printing head parameters: [0200] Pixels per inch:
300 [0201] Resistor size: 2.times.(31.5.times.180) microns (split
resistor) [0202] Resistance: 3000 Ohm [0203] Glaze Thickness: 200
microns [0204] Pressure: 3 lb/linear inch [0205] Dot pattern:
Slanted grid.
[0206] The cyan color-forming layer is printed as shown in the
table below. The line cycle time is divided into individual pulses
of about 4.5% duty cycle. The thermal imaging member is preheated
by contact with the thermal printing head glaze at the heat sink
temperature over a distance of about 0.3 mm.
TABLE-US-00004 Cyan printing Heat sink 50.degree. C. temperature
Dpi 300 (transport direction) Voltage 38 Line speed 0.2 inch/sec
Pulse 280 microsec interval # pulses used 33-42
[0207] Referring now to FIG. 1, a second preferred thermal imaging
member 10 according to the invention is shown in schematic form.
All layers were coated from aqueous fluids which contained small
amounts of a coating aid, Zonyl FSN, available from Dupont Co.,
Wilmington, Del.
[0208] The substrate 12 is a filled, white, oriented polypropylene
base of thickness about 200 microns, FPG200, available from Yupo
Corporation America, Chesapeake, Va. 23320.
[0209] An adhesion-promoting layer 14 overlies the substrate 12,
composed of the CP655 (a latex available from Dow Chemical Co.,
Midland, Mich., 48% by weight), CP692 (a latex available from Dow
Chemical Co., Midland, Mich., 31% by weight) and POVAL MP103 (a
fully hydrolyzed poly(vinyl alcohol) available from Kuraray
America, Inc., New York, N.Y., 21% by weight). This layer has a
coverage of 7.5 g/m.sup.2.
[0210] Overlying the adhesion-promoting layer 14 is an oxygen
barrier layer 16 composed of the above-mentioned POVAL MP103 (89.3%
by weight) and glyoxal (a crosslinker, 10.7% by weight). This layer
has a coverage of 1.2 g/m.sup.2.
[0211] Overlying the oxygen barrier layer 16 is a cyan
color-forming layer 18 composed of a cyan color-former having
melting point 210.degree. C., dye X of the present invention,
1,2-bis(2,4-dimethylphenoxy)ethane (a thermal solvent having
melting point 112.degree. C., coated as an aqueous dispersion of
crystals having average particle size under 1 micron, 6 parts by
weight), a phenolic antioxidant/developer (Anox 29, having melting
point 161-164.degree. C., available from Great Lakes Chemical Co.,
West Lafayette, Ind., coated as an aqueous dispersion of crystals
having average particle size under 1 micron, 1 part by weight),
Lowinox 1790 (a second phenolic antioxidant/stabilizer, available
from Great Lakes Chemical Co., West Lafayette, Ind., coated as an
aqueous dispersion of crystals having average particle size under 1
micron, 1.5 parts by weight), a binder (poly(vinyl alcohol), Celvol
205, available from Celanese, Dallas, Tex., 7 parts by weight) and
glyoxal (0.42 parts by weight). This layer has a coverage of 3.35
g/m.sup.2.
[0212] Overlying the cyan color-forming layer 18 is a barrier layer
20 that contains a fluorescent brightener. This layer is composed
of the above-mentioned POVAL MP103 (82% by weight), glyoxal (8% by
weight) and Leucophor BCF P115 (a fluorescent brightener, available
from Clariant Corp., Charlotte, N.C., 10% by weight). This layer
has a coverage of 2 g/m.sup.2.
[0213] Overlying the barrier layer 20 is a thermally-insulating
interlayer 22 composed of the above-mentioned CP692(40% by weight)
and the above-mentioned CP655 (60% by weight). This layer has a
coverage of 21 g/m.sup.2.
[0214] Overlying the thermally-insulating interlayer 22 is a
barrier layer 24 composed the above-mentioned POVAL MP103 (94% by
weight) and glyoxal (a crosslinker, 6% by weight). This layer has a
coverage of 1.5 g/m.sup.2.
[0215] Overlying the barrier layer 24 is a magenta color-forming
layer 26, composed of a magenta color-former, Dye IV described in
U.S. patent application Ser. No. 11/433808, filed May 12, 2006,
having a melting point of 152.degree. C. (1 part by weight); a
phenolic antioxidant/developer (Anox 29, having melting point
161-164.degree. C., available from Great Lakes Chemical Co., West
Lafayette, Ind., coated as an aqueous dispersion of crystals having
average particle size under 1 micron, 3 parts by weight), Lowinox
1790 (a second phenolic antioxidant/stabilizer, available from
Great Lakes Chemical Co., West Lafayette, Ind., coated as an
aqueous dispersion of crystals having average particle size under 1
micron, 1 part by weight), a binder (poly(vinyl alcohol, Celvol
540, available from Celanese, Dallas, Tex., 3.2 parts by weight)
and glyoxal (0.19 parts by weight). This layer has a coverage of
2.38 g/m.sup.2.
[0216] Overlying the magenta color-forming layer 26 is a barrier
layer 28 that contains a fluorescent brightener. This layer is
composed of the above-mentioned POVAL MP103 (82% by weight),
glyoxal (8% by weight) and the above-mentioned Leucophor BCF P115.
This layer has a coverage of 1 g/m.sup.2.
[0217] Overlying the barrier layer 28 is a second
thermally-insulating interlayer 30 composed of the above-mentioned
CP655 (48% by weight), the above-mentioned CP692 (31% by weight)
and the above-mentioned POVAL MP103 (21% by weight). This layer has
a coverage of 3 g/m.sup.2.
[0218] Overlying the second thermally-insulating interlayer 30 is a
barrier layer 32 composed the above-mentioned POVAL MP103 (94% by
weight) and glyoxal (a crosslinker, 6% by weight). This layer has a
coverage of 1 g/m.sup.2.
[0219] Overlying the barrier layer 32 is a yellow color-forming
layer 34 composed of Dye XI (having melting point 202-203.degree.
C.) described in U.S. Pat. No. 7,279,264, (59.6% by weight),
Lowinox 1790 (a phenolic antioxidant/stabilizer, available from
Great Lakes Chemical Co., West Lafayette, Ind., coated as an
aqueous dispersion of crystals having average particle size under 1
micron, 7.6% by weight), a binder (poly(vinyl alcohol), Celvol 540,
available from Celanese, Dallas, Tex., 32.8% by weight). This layer
has a coverage of 1.99 g/m.sup.2.
[0220] Overlying the yellow color-forming layer 34 is a barrier
layer 36 composed of a fully hydrolyzed poly(vinyl alcohol), Celvol
325, available from Celanese, Dallas, Tex. (94% weight) and glyoxal
(6% by weight). This layer has a coverage of 0.5 g/m.sup.2.
[0221] Deposited on the barrier layer 36 is an ultra-violet
blocking layer 38 composed of a nanoparticulate grade of titanium
dioxide (MS-7, available from Kobo Products Inc., South Plainfield,
N.J., 62% by weight), the above-mentioned POVAL MP103 (35% by
weight) and glyoxal (3% by weight). This layer has a coverage of
about 2 g/m.sup.2.
[0222] Deposited on the ultra-violet blocking layer 38 is an
overcoat 40 composed of a latex (CR-717, available from Lubrizol
Co., Wickliffe, Ohio, 34% by weight), a styrene/maleic acid
copolymer (SMA 1000MA, available from Sartomer Company, Wilmington,
Pa., 6% by weight), the above-mentioned POVAL MP103 (5% by weight),
a rheology modifier (Rheolate 310, available from Elementis
Specialties, Inc, Hightstown, N.J., 3% by weight), a crosslinker
(Bayhydur VPLS 2336, available from BayerMaterialScience,
Pittsburgh, Pa., 34% by weight), zinc stearate (a meltable
lubricant, available from Ferro Co., Cleveland, Ohio, 18% by
weight). This layer has a coverage of 1 g/m.sup.2.
[0223] On the reverse side of substrate 12 is an anticurl layer 42
comprising gelatin, of coverage 5 g/m.sup.2.
[0224] The imaging members described above can be printed using
techniques such as those described in U.S. Pat. No. 6,801,233, U.S.
patent application Ser. No. 11/400734, filed Apr. 6, 2006, U.S.
patent application Ser. No.. 11/400735, filed Apr. 6, 2006, and
United States patent application Ser. No. ______, entitled "Print
Head Pulsing Techniques for Multicolor Printers" of even date
herewith.
[0225] The invention will now be described further in detail with
respect to specific embodiments by way of an example, it being
understood that this is intended to be illustrative only and the
invention is not limited to the materials, amounts, procedures and
process parameters, etc. recited herein. All parts and percentages
recited are by weight unless otherwise specified.
Example XI
[0226] Synthesis of 4-methylacetanilide
[0227] A 22 L flask immersed in a water bath (25 C) was charged
with p-toluidine (2.5 kg, 23.4 mole) in acetonitrile (8 L). Acetic
anhydride (2.5 kg, 24.5 mole) added over -2 hours. During the
addition the product crystallized and the batch temperature rose to
.about.45 C. The batch was allowed to cool to ambient temperature
overnight. The product was filtered off, washed with water and
dried yielding a white solid (2.7 kg, 18.1 mole, 77%). A second
crop of 200-300 g was obtained from the filtrate (.about.3:1
water:acetonitrile). This material was characterized by NMR
spectroscopy.
Synthesis of N-Methallyl-4-methylacetanilide
[0228] A 2 L reactor with batch temperature control was charged
with 4-methylacetanilide (149 g, 1 mole), potassium hydroxide
pellets (87%, 100 g,) in dimethylsulfoxide (650 mL) at 35 C.
3-Chloro-2-methyl-propene (90%, 112.7 g , 1.12 moles) was charged
over 60 min holding the batch at 35 C. HPLC indicates complete
reaction after 3 h. Water (600 mL) and heptane (200 mL) were added
to the reactor. The lower layer was separated and discarded. The
organic layer was washed with water (2.times.200 ml) then distilled
to remove residual water (104 C pot temperature). Approximately 50
ml of water was removed. This yielded 278.5 g product of 67.6 wt %
(188.2 g, 92.6% yield). This mixture was then used directly in the
next step.
Synthesis of N-Acetyl-3,3,5-trimethylindoline
[0229] A 2 L reactor with batch temperature control was charged
with aluminum chloride (340 g) and chlorobenzene (350 mL) and held
at 80 C. N-methallyl-4-methylacetanilide (188.2 g
heptane/chlorobenzene solution from the preceding step) was added
over approximately one hour holding the batch at 80 C. The batch
was held at 80 C for 2 hours. The batch was cooled to 25 C then
quenched into a mixture of toluene (500 mL) and water (1400 mL).
The aqueous layer was removed and the milky organic layer was
washed with 6M HCl (2.times.200 ml) resulting in a clear green
solution. This solution of N-Acetyl-3,3,5-trimethylindoline is used
directly in the next step.
Synthesis of 3,3,5-trimethylindoline
[0230] The N-Acetyl-3,3,5-trimethylindoline solution from the
previous step was returned to the 2 L reactor. Hydrochloric acid
(6M, 500 mL) was added and the batch was held at reflux (97 C
batch, 101 jacket) overnight. The batch was cooled to 70 C and the
aqueous layer containing the product was collected. Crystals of the
indoline HCl-salt form upon further cooling of the aqueous
solution. The resulting suspension was treated with 456 NaOH (300
mL) bringing the pH to >10. Hexane (100 mL) was added to
facilitate the phase split. The organic layer was separated, washed
with water then concentrated under reduced pressure yielding crude
3,3,5-trimethylindoline (134 g) as a dark oil. The crude indoline
was vacuum distilled yielding a colorless liquid (116 g, by
.about.110 @ 3 mm, 78% yield from N-Methallyl-4-methylacetanilide).
The structure and purity were confirmed by NMR spectroscopy and
HPLC.
Synthesis of
3'-(3,3,5-trimethylindolino)-6'-chloro-4,5,6,7-tetrafluorofluoran
[0231] In a 12 liter flask was added sulfolane (3500 mL) followed
by 3',6'-Dichloro-4,5,6,7-tetrafluorofloran (826 g, 1.872 mole) and
stirred. Aluminum chloride (1248 g, 9.36 mole) was added next in
portions to keep the temperature under control. The temperature was
allowed to reach 80 C and addition of the 3,3,5-trimethylindoline
(300 g, 1.872 mole) was started with an addition funnel into the
center of the vortex. After the 3,3,5-trimethylindoline was added,
2,6-lutidine (401 g, 3.744 mole) was similarly added. The reaction
was allowed to stir for 30 minutes at temperature (70-80 C) then
cooled. The warm reaction mixture (60 C) was poured into ice water
(40 L) with rapid stirring. The light blue solid was collected by
vacuum filtration, then washed with additional water (10 L) until
the eluent, for all intents and purposes, became colorless.
[0232] The flocculent solid was washed with acetonitrile (2.times.2
L). The acetonitrile removed the water entrained in the solid,
reduced the volume by 50% , and removed some of the dark blue
impurities giving a pale blue product.
[0233] The solid was re-suspended in of acetonitrile (6.5 L) and
heated. As heating proceeds, the suspended solid swells and
thickens. The stirring rate must be increased to enable adequate
stirring. After stirring at reflux for 15 minutes, the suspension
was allowed to cool overnight to ambient temperature. The solid was
collected by vacuum filtration, and washed with cold acetonitrile
until the eluent was essentially colorless. The solid was dried
overnight in a vacuum oven at 80 C (1013 g, 1,80 mole, 96%).
Synthesis of
3'-(3,3,5-trimethylindolino)-6'-(2,4-dimethylanilino)-4,5,6,7-tetrafluoro-
fluoran
[0234] Diethylene glycol dimethyl ether (800 mL) was placed in a
2-L 3-necked flask and heating commenced. Anhydrous zinc chloride
(117.7 g, 0.885 mole) was added but even after 1 hour of stirring
at 120 C it had not dissolved completely. One equivalent of
2,4-dimethylaniline (21 g, 0.177 mole) was added. The solution
typically turns pale brown and all the zinc chloride dissolves.
3'-(3,3,5-trimethylindolino)-6'-chloro-4,5,6,7-tetrafluorofloran
(100 g, 0.177 mole) was added next as fast as it would dissolve.
After stirring at 120 C for 30 minutes, a second equivalent of
2,4-dimethylaniline (21 g, 0.177 mole) was added and the
temperature raised to 138 C. The blue solution was sampled for HPLC
analysis after 4 hours at 138 C and found to be 1:1 starting
material to product - none of the fluorine displacement by-product
was visible by HPLC. A third equivalent of the aniline (21 g, 0.177
mole) was added and the reaction was again sampled after 5.5 hours.
Analysis showed 70% completion. The remaining 1/2 equivalent of the
aniline (10.5 g, 0.088 mole) was added and the reaction was allowed
to continue overnight. After 16 hours, the dye formation was
complete with very little unreacted starting material or side
products. The reaction was allowed to cool to .about.60 C then
poured into 4-liters of rapidly stirring ice water with 50 mL of
concentrated hydrochloric acid added. A dark, blue-black solid
separated out. After stirring for 30 minutes, the solid was
collected by vacuum filtration. The solid was washed with
additional water (2 L). The wet cake (529 g) was then dissolved in
ethyl acetate (3.0 L). Once a solution was achieved, a 10% by
weight aqueous solution of sodium acetate (1.0 L) was added and
allowed to stir for 30 minutes. The stirring was stopped and the
aqueous portion was removed. The aqueous sodium acetate extraction
was repeated a total of two times (2.times.1.0 L) followed by
extraction with water (2.times.1.0 L). The final phase split was
allowed to settle overnight before the water was removed. If the
phase split does not occur, the amount of ethyl acetate that the
dye is dissolved in must be increased. The ethyl acetate/water
azeotrope was distilled off until nearly 1.5 liters of solution had
been removed (some loss due to evaporation). The remainder was then
transferred into a smaller vessel and distillation was continued.
Another 1000 mL of solution was removed, leaving about 500 mL in
the vessel. The solution in the pot now took on a purple-blue
color. Heptane was added (750 mL), as well as a few seed crystals.
The distillation was continued until solid was visible in the
stirrring solution; (an additional 100 mL of EtOAc distilled over).
Once solid was visible, heating was stopped and the suspension
allowed to cool to RT. The solid was collected and washed with
heptane, dried overnight in a vacuum oven at 60 C. Dried recovery
=89.4 g. This was dissolved in 200 mL of boiling chlorobenzene. The
initial color of the solution of dye was blue, but as the residual
water azeotropes off (just a few minutes) the solution turn purple.
Heptane (450 mL) was then poured slowly into the boiling solution -
the addition is such that the reflux of solvent is never allowed to
stop; a few seed crystals were also added. Once all of the heptane
had been added, heating was stopped, and the solution allowed to
cool to RT. Solid began precipitating out nearly as soon as heating
is stopped. The solid is collected, washed with cold 20%
Chlorobenzene/Heptane, followed by heptane alone. The solid was
dried in a vacuum oven at 60 C overnight. (Yield: 76 g, 0.117 mole,
66%). The color of the material was a pale blue and the purity by
HPLC was 97% by weight. The dye was characterized by mass
spectrometry, DSC-TGA and NMR spectroscopy.
[0235] Although the invention has been described in detail with
respect to various preferred embodiments, it is not intended to be
limited thereto, but rather those skilled in the art will recognize
that variations and modifications are possible which are within the
spirit of the invention and the scope of the appended claims.
* * * * *