U.S. patent application number 11/604942 was filed with the patent office on 2008-05-29 for process for the synthesis of hydroxy aromatic acids.
Invention is credited to Joachim C. Ritter.
Application Number | 20080125604 11/604942 |
Document ID | / |
Family ID | 39167860 |
Filed Date | 2008-05-29 |
United States Patent
Application |
20080125604 |
Kind Code |
A1 |
Ritter; Joachim C. |
May 29, 2008 |
PROCESS FOR THE SYNTHESIS OF HYDROXY AROMATIC ACIDS
Abstract
Hydroxy aromatic acids are produced in high yields and high
purity (>95%) from halogenated aromatic acids in a reaction
mixture containing a copper source and a ligand that coordinates to
copper.
Inventors: |
Ritter; Joachim C.;
(Wilmington, DE) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY;LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1122B, 4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
39167860 |
Appl. No.: |
11/604942 |
Filed: |
November 28, 2006 |
Current U.S.
Class: |
562/476 ;
562/475; 562/477 |
Current CPC
Class: |
C07C 51/367 20130101;
C07C 51/02 20130101; C07C 51/412 20130101; C07C 65/01 20130101;
C07C 51/367 20130101; C07C 51/412 20130101; C07C 51/412 20130101;
C07C 51/412 20130101; C07C 63/00 20130101; C07C 51/02 20130101;
C07C 65/10 20130101; C07C 65/05 20130101; C07C 65/05 20130101; C07C
65/03 20130101; C07C 65/05 20130101; C07C 65/10 20130101; C07C
65/03 20130101; C07C 65/03 20130101; C07C 65/10 20130101; C07C
51/02 20130101; C07C 51/367 20130101; C07C 51/02 20130101; C07C
51/367 20130101 |
Class at
Publication: |
562/476 ;
562/475; 562/477 |
International
Class: |
C07C 65/03 20060101
C07C065/03; C07C 65/01 20060101 C07C065/01 |
Claims
1. A process for preparing a hydroxy aromatic acid that is
described generally by the structure of Formula I ##STR00035##
wherein Ar is a C.sub.6.about.C.sub.20 arylene radical, n and m are
each independently a nonzero value, and n+m is less than or equal
to 8, comprising the steps of (a) contacting a halogenated aromatic
acid that is described generally by the structure of Formula II,
##STR00036## wherein each X is independently Cl, Br or I, and Ar, n
and m are as set forth above, with a base in water to form
therefrom the corresponding m-basic salt of the halogenated
aromatic acid in water; (b) contacting the m-basic salt of the
halogenated aromatic acid with a base in water, and with a copper
source in the presence of a ligand that coordinates to copper, to
form the m-basic salt of a hydroxy aromatic acid from the m-basic
salt of the halogenated aromatic acid at a solution pH of at least
about 8, wherein the ligand comprises a Schiff base; (c)
optionally, separating the m-basic salt of the hydroxy aromatic
acid from the reaction mixture in which it is formed; and (d)
contacting the m-basic salt of the hydroxy aromatic acid with acid
to form therefrom an n-hydroxy aromatic acid.
2. A process according to claim 1 wherein, in step (a), the
halogenated aromatic acid is contacted with at least about two
normal equivalents of water-soluble base per equivalent of
halogenated aromatic acid.
3. A process according to claim 1 wherein, in step. (b), the
m-basic salt of the halogenated aromatic acid is contacted with at
least about two normal equivalents of water-soluble base per
equivalent of the m-basic salt of the halogenated aromatic
acid.
4. A process according to claim 1 wherein, in steps (a) and (b), a
total of about n+m+1 normal equivalents of water-soluble base are
added to the reaction mixture per equivalent of the halogenated
aromatic acid.
5. A process according to claim 1 wherein the copper source
comprises Cu(0), a Cu(I) salt, a Cu(II) salt, or a mixture
thereof.
6. A process according to claim 1 wherein the copper source is
selected from the group consisting of CuCl, CuBr, CuI,
Cu.sub.2SO.sub.4, CuNO.sub.3, CuCl.sub.2, CuBr.sub.2, CuI.sub.2,
CuSO.sub.4, Cu (NO.sub.3).sub.2, and mixtures thereof.
7. A process according to claim 1 wherein the ligand is described
generally by the following Formula IV:. ##STR00037## wherein
R.sup.1, R.sup.2 and R.sup.3 are each independently selected from
substituted and unsubstituted C.sub.1-C.sub.16 n-alkyl, iso-alkyl
and tertiary alkyl groups; and substituted and unsubstituted
C.sub.6-C.sub.30 aryl and heteroaryl groups.
8. A process according to claim 1 wherein the ligand is described
generally by the following Formula V ##STR00038## wherein A is
selected from the group consisting of ##STR00039## R.sup.1,
R.sup.2, R.sup.3 and R.sup.4 are each independently selected from
substituted and unsubstituted C.sub.1-C.sub.16 n-alkyl, iso-alkyl
and tertiary alkyl groups; and substituted and unsubstituted
C.sub.6-C.sub.30 aryl and heteroaryl groups; R.sup.5 is selected
from H, substituted and unsubstituted C.sub.1-C.sub.16 n-alkyl,
iso-alkyl and tertiary alkyl groups; and substituted and
unsubstituted C.sub.6-C.sub.30 aryl and heteroaryl groups; and
halogen; R.sup.6, R.sup.7, R.sup.8 and R.sup.9 are each
independently selected from H or a substituted or unsubstituted
C.sub.1-C.sub.16 n-alkyl, iso-alkyl or tertiary alkyl group; and
n=0 or 1.
9. A process according to claim 8 wherein n=0; or R.sup.3 and
R.sup.4 are taken together to form the CH.sub.3--C--C--CH.sub.3
moiety bonded to the two nitrogen atoms.
10. A process according to claim 1 wherein the ligand is selected
from N,N'-dimesityl-2,3-diiminobutane and
N,N'-di(trifluoromethylbenzene)-2,3-diiminoethane.
11. A process according to claim 1 further comprising a step of
combining the copper source with the ligand before adding them to
the reaction mixture.
12. A process according to claim 1 wherein the copper source
comprises CuBr.
13. A process according to claim 1 wherein a base comprises one or
more of a water-soluble hydroxide, phosphate, carbonate, or
bicarbonate of one or more of Li, Na, K, Mg, or Ca.
14. A process according to claim 1 wherein copper is provided in an
amount of between about 0.1 and about 5 mol % based on moles of
halogenated aromatic acid.
15. A process according to claim 1 wherein the ligand is provided
in an amount of between about one and about two molar equivalents
per mole of copper.
16. A process according to claim 1 further comprising a step of
converting the n-hydroxy aromatic acid to an n-alkoxy aromatic
acid.
17. A process according to claim 16 wherein the n-hydroxy aromatic
acid is contacted under basic conditions with a dialkyl sulfate of
the formula R.sup.9 R.sup.10 SO.sub.4 wherein R.sup.9 and R.sup.10
are each independently a substituted or unsubstituted C.sub.1-10
alkyl group.
18. A process according to claim 1 further comprising a step of
subjecting the n-hydroxy aromatic acid to a reaction to prepare
therefrom a compound, monomer, oligomer or polymer.
19. A process according to claim 18 wherein a polymer prepared
comprises a pyridobisimidazole-2,6-diyl(2,5-dihydroxy-p-phenylene)
polymer.
20. A process according to claim 16 further comprising a step of
subjecting the n-alkoxy aromatic acid to a reaction to prepare
therefrom a compound, monomer, oligomer or polymer.
Description
TECHNICAL FIELD
[0001] This invention relates to the manufacture of hydroxy
aromatic acids, which are valuable for a variety of purposes such
as use as intermediates or as monomers to make polymers.
BACKGROUND
[0002] Hydroxy aromatic acids are useful as intermediates and
additives in the manufacture of many valuable materials including
pharmaceuticals and compounds active in crop protection, and are
also useful as monomers in the production of polymers. Salicylic
acid (o-hydroxybenzoic acid), for example, is used in the
manufacture of aspirin and has other pharmaceutical applications.
Esters of p-hydroxybenzoic acid, known as "parabens", are used as
food and cosmetic preservatives. P-hydroxybenzoic acid and
6-hydroxy-2-naphthoic acid are each used as a component of liquid
crystalline polymers.
[0003] Various preparations of hydroxybenzoic acids, including
2,5-dihydroxyterephthalic acid ("DHTA"), are known. Marzin, in
Journal fuer Praktische Chemie, 1933, 138, 103-106, teaches the
synthesis of 2,5-dihydroxyterephthalic acid ("DHTA") from
2,5-dibromoterephthalic acid ("DBTA") in the presence of copper
powder.
[0004] Singh et al, in Jour. Indian Chem. Soc., Vol. 34, No. 4,
pages 321-323 (1957), report the preparation of a product that
includes DHTA by the condensation of DBTA with phenol in the
presence of KOH and copper powder.
[0005] Rusonik et al, Dalton Trans., 2003, 2024-2028, describe the
transformation of 2-bromobenzoic acid into salicylic acid, benzoic
acid, and diphenoic acid in a reaction catalyzed by Cu(I) in the
presence of various ligands. A tertiary tetraamine minimizes the
formation of diphenoic acid in use with Cu(I).
[0006] Comdom et al, Synthetic Communications, 32(13), 2055-59
(2002), describe a process for the synthesis of salicylic acids
from 2-chlorobenzoic acids. Stoichiometric amounts of pyridine (0.5
to 2.0 moles per mole of 2-chlorobenzoic acid) are used such as at
least 1.0 mole pyridine per mole 2-chlorobenzoic acid. Cu powder is
used as a catalyst along with the pyridine.
[0007] Gelmont et al, Organic Process Research & Development,
6(5), 591-596 (2002), and U.S. Pat. No. 5,703,274, describe a
process for the preparation of 5-hydroxyisophthalic acid by
hydrolyzing 5-bromoisophthalic acid, mixtures of 5-bromoisophthalic
acid, dibromoisophthalic acid isomers, and salts thereof in an
aqueous alkaline solution in the presence of a copper catalyst at a
temperature of 100 to 270.degree. C.
[0008] Israeli Patent 112,706 discloses a process for the
preparation of 4-hydroxyphthalic acid, and a mixture of 3- and
4-hydroxyphthalic acids, by hydrolyzing the corresponding
bromophthalic acids in an aqueous alkaline solution in the presence
of a copper catalyst at a temperature of 100 to 160.degree. C.
Examples of copper catalysts disclosed include Cu(0), CuCl,
CuCl.sub.2, Cu.sub.2O, CuO, CuBr.sub.2, CuSO.sub.4, Cu(OH).sub.2,
and copper (II) acetate.
[0009] The various prior art processes for making hydroxybenzoic
acids are characterized by long reaction times, limited conversion
resulting in significant productivity loss, or the need to run
under pressure and/or at higher temperatures (typically 140 to
250.degree. C.) to get reasonable rates and productivity. A need
therefore remains for a process by which hydroxybenzoic acids can
be produced economically; with low inherent operational difficulty;
and with high yields and high productivity in small- and
large-scale operation, and in batch and continuous operation.
SUMMARY
[0010] One embodiment of this invention provides a process for
preparing a hydroxy aromatic acid that is described generally by
the structure of Formula I
##STR00001##
wherein Ar is a C.sub.6.about.C.sub.20 arylene radical, n and m are
each independently a nonzero value, and n+m is less than or equal
to 8, by (a) contacting a halogenated aromatic acid that is
described generally by the structure of Formula II,
##STR00002##
wherein each X is independently Cl, Br or I, and Ar, n and m are as
set forth above, with a base in water to form therefrom the
corresponding m-basic salt of the halogenated aromatic acid in
water; (b) contacting the m-basic salt of the halogenated aromatic
acid with a base in water, and with a copper source in the presence
of a ligand that coordinates to copper, to form the m-basic salt of
a hydroxy aromatic acid from the m-basic salt of the halogenated
aromatic acid at a solution pH of at least about 8; (c) optionally,
separating the m-basic salt of the hydroxy aromatic acid from the
reaction mixture in which it is formed; and (d) contacting the
m-basic salt of the hydroxy aromatic acid with acid to form
therefrom a n-hydroxy aromatic acid.
[0011] Yet another embodiment of this invention provides a process
for preparing an n-alkoxy aromatic acid by preparing an n-hydroxy
aromatic acid in the manner described above and then converting the
n-hydroxy aromatic acid to an n-alkoxy aromatic acid.
[0012] Yet another embodiment of this invention consequently
provides a process for preparing an n-alkoxy aromatic acid that is
described generally by the structure of Formula VI
##STR00003##
wherein Ar is a C.sub.6.about.C.sub.20 arylene radical, each
R.sup.9 is independently a substituted or unsubstituted C.sub.1-10
alkyl group, n and m are each independently a nonzero value, and
n+m is less than or equal to 8, by (a) contacting a halogenated
aromatic acid that is described generally by the structure of
Formula II,
##STR00004##
wherein each X is independently Cl, Br or I, and Ar, n and m are as
set forth above, with a base in water to form therefrom the
corresponding m-basic salt of the halogenated aromatic acid in
water; (b) contacting the m-basic salt of the halogenated aromatic
acid with a base in water, and with a copper source in the presence
of a ligand that coordinates to copper, to form the m-basic salt of
a hydroxy aromatic acid from the m-basic salt of the halogenated
aromatic acid at a solution pH of at least about 8; (c) optionally,
separating the m-basic salt of the hydroxy aromatic acid from the
reaction mixture in which it is formed; (d) contacting the m-basic
salt of the hydroxy aromatic acid with acid to form therefrom an
n-hydroxy aromatic acid that is described generally by the
structure of Formula I,
##STR00005##
wherein Ar, n and m are as set forth above; and (e) converting the
n-hydroxy aromatic acid to an n-alkoxy aromatic acid that is
described generally by the structure of Formula VI, wherein Ar,
R.sup.9, n and m are as set forth above.
[0013] Yet another embodiment of this invention provides a process
for preparing a 2,5-dihydroxyterephthalic acid or a
2,5-dialkoxyterephthalic acid as described above that further
includes a step of subjecting the 2,5-dihydroxyterephthalic acid or
the 2,5-dialkoxyterephthalic acid to a reaction to prepare
therefrom a compound, monomer, oligomer or polymer.
[0014] Yet another embodiment of this invention consequently
provides a process for preparing a compound, monomer, oligomer or
polymer by preparing a hydroxy aromatic acid that is described
generally by the structure of Formula I
##STR00006##
wherein Ar is a C.sub.6.about.C.sub.20 arylene radical, n and m are
each independently a nonzero value, and n+m is less than or equal
to 8, by (a) contacting a halogenated aromatic acid that is
described generally by the structure of Formula II,
##STR00007##
wherein each X is independently Cl, Br or I, and Ar, n and m are as
set forth above, with a base in water to form therefrom the
corresponding m-basic salt of the halogenated aromatic acid in
water; (b) contacting the m-basic salt of the halogenated aromatic
acid with a base in water, and with a copper source in the presence
of a ligand that coordinates to copper, to form the m-basic salt of
a hydroxy aromatic acid from the m-basic salt of the halogenated
aromatic acid at a solution pH of at least about 8; (c) optionally,
separating the m-basic salt of the hydroxy aromatic acid from the
reaction mixture in which it is formed; (d) contacting the m-basic
salt of the hydroxy aromatic acid with acid to form therefrom an
n-hydroxy aromatic acid; (e) optionally, converting the n-hydroxy
aromatic acid to a n-alkoxy aromatic acid; and (f) subjecting the
n-hydroxy aromatic acid and/or the n-alkoxy aromatic acid to a
reaction to prepare therefrom a compound, monomer, oligomer or
polymer.
[0015] In yet another embodiment, the ligand in one or more of the
processes described herein may be a Schiff base.
DETAILED DESCRIPTION
[0016] This invention provides a high yield and high productivity
process for preparing a hydroxy aromatic acid as described
generally by the structure of Formula I
(COOH).sub.m--Ar--(OH).sub.n I
by contacting a halogenated aromatic acid as described generally by
the structure of Formula II
(COOH).sub.m--Ar--(X).sub.n II
with base to form the m-basic salt of the halogenated aromatic
acid; contacting the m-basic salt of the halogenated aromatic acid
with base, and with a copper source in the presence of a ligand
that coordinates to copper, to form the m-basic salt of an
n-hydroxy aromatic acid; and then contacting the dibasic salt of
the n-hydroxy aromatic acid with acid to form the n-hydroxy
aromatic acid product.
[0017] In both Formulae I and II, Ar is a C.sub.6.about.C.sub.20
arylene radical, n and m are each independently a nonzero value,
and n+m is less than or equal to 8; and in Formula II, each X is
independently Cl, Br or I. The arylene radical denoted by "--Ar--"
is a multi-valent aromatic radical formed by the removal of two or
more hydrogens from different carbon atoms on the aromatic ring, or
on the aromatic rings when the structure is multicyclic. There is
consequently, for example, the possibility in the arylene radical
that hydrogens may be removed from two up to all six carbon atoms
on a benzyl ring, or hydrogens may be removed from any two and up
to eight positions on either one or both rings of a naphthyl
radical.
[0018] The arylene radical, "Ar", may be substituted or
unsubstituted. The arylene radical, when unsubstituted, is a
univalent group containing only carbon and hydrogen. In the arylene
radical, however, one or more O or S atoms may optionally be
substituted for any one or more of the in-chain or in-ring carbon
atoms, provided that the resulting structure contains no --O--O--
or --S--S-- moieties, and provided that no carbon atom is bonded to
more than one heteroatom. One example of a suitable arylene radical
is phenylene, as shown below.
##STR00008##
[0019] An "m-basic salt", as the term is used herein, is the salt
formed from an acid that contains in each molecule m acid groups
having a replaceable hydrogen atom.
[0020] Various halogenated aromatic acids, to be used as a starting
material in the process of this invention, are commercially
available. For example, 2-bromobenzoic acid is available from
Aldrich Chemical Company (Milwaukee, Wis.). It can be synthesized,
however, by oxidation of bromomethylbenzene as described in Sasson
et al, Journal of Organic Chemistry (1986), 51(15), 2880-2883.
Other halogenated aromatic acids that can be used include without
limitation 2,5-dibromobenzoic acid, 2-bromo-5-nitrobenzoic acid,
2-bromo-5-methylbenzoic acid, 2-chlorobenzoic acid,
2,5-dichlorobenzoic acid, 2-chloro-3,5-dinitrobenzoic acid,
2-chloro-5-methylbenzoic acid, 2-bromo-5-methoxybenzoic acid,
5-bromo-2-chlorobenzoic acid, 2,3-dichlorobenzoic acid,
2-chloro-4-nitrobenzoic acid, 2,5-dichloroterephthalic acid, and
2-chloro-5-nitrobenzoic acid, all of which are commercially
available.
[0021] Other halogenated aromatic acids useful as a starting
material in the process of this invention include those shown in
the left column of the table below, wherein X.dbd.Cl, Br or I, and
wherein the corresponding hydroxy aromatic acid produced therefrom
by the process of this invention is shown in the right column:
TABLE-US-00001 (COOH).sub.m--Ar--(X).sub.n I
(COOH).sub.m--Ar--(OH).sub.n II ##STR00009## ##STR00010##
##STR00011## ##STR00012## ##STR00013## ##STR00014## ##STR00015##
##STR00016## ##STR00017## ##STR00018## ##STR00019## ##STR00020##
##STR00021## ##STR00022## ##STR00023## ##STR00024## ##STR00025##
##STR00026##
[0022] In step (a), a halogenated aromatic acid is contacted with
base in water to form therefrom the corresponding m-basic salt of
the halogenated aromatic acid. In step (b), the m-basic salt of the
halogenated aromatic acid is contacted with base in water, and with
a copper source in the presence of a ligand that coordinates to
copper, to form the m-basic salt of a hydroxy aromatic acid from
the m-basic salt of the halogenated aromatic acid.
[0023] The base used in step (a) and/or step (b) may be an ionic
base, and may in particular be one or more of a hydroxide,
carbonate, bicarbonate, phosphate or hydrogen phosphate of one or
more of Li, Na, K, Mg or Ca. The base used may be water-soluble,
partially water-soluble, or the solubility of the base may increase
as the reaction progresses and/or as the base is consumed. NaOH and
Na.sub.2CO.sub.3 are preferred, but other suitable organic bases
may be selected, for example, from the group consisting of
trialkylamines (such as tributylamine);
N,N,N',N'-tetramethylethylenediamine; and N-alkyl imidazoles (for
example, N-methylimidazole). In principle any base capable of
maintaining a pH above 8 and/or binding the acid produced during
the reaction of the halogenated aromatic acid is suitable.
[0024] The specific amounts of base to be used in steps (a) and/or
(b) depend on the strength of the base. In step (a), a halogenated
aromatic acid is preferably contacted with at least about m
equivalents of water-soluble base per equivalent of halogenated
aromatic acid. One "equivalent" as used for a base in this context
is the number of moles of base that will react with one mole of
hydrogen ions; for an acid, one equivalent is the number of moles
of acid that will supply one mole of hydrogen ions.
[0025] In step (b), enough base should be used to maintain a
solution pH of at least about 8, or at least about 9, or at least
about 10, and preferably between about 9 and about 11. Thus,
typically in step (b), the dibasic salt of the halogenated aromatic
acid is contacted with at least about n equivalents of base, such
as a water-soluble base, per equivalent of the m-basic salt of the
halogenated aromatic acid.
[0026] In alternative embodiments, however, it may be desirable in
steps (a) and (b) to use a total of at least about n+m+1
equivalents of base, such as a water-soluble base, in the reaction
mixture per equivalent of the halogenated aromatic acid originally
used at the start of the reaction. A base used in an amount as
described above is typically a strong base, and is typically added
at ambient temperature. The base used in step (b) may be the same
as, or different than, the base used in step (a).
[0027] As mentioned above, in step (b), the m-basic salt of the
halogenated aromatic acid is also contacted with a copper source in
the presence of a ligand that coordinates to copper. The copper
source and the ligand may be added sequentially to the reaction
mixture, or may be combined separately (for example, in a solution
of water or acetonitrile) and added together. The copper source may
be combined with the ligand in the presence of oxygen in water, or
be combined with a solvent mixture containing water.
[0028] From the presence together in the reaction mixture of the
copper source and the ligand, in a basic solution of the m-basic
salt of the halogenated aromatic acid, there is obtained an aqueous
mixture containing the m-basic salt of a hydroxy aromatic acid,
copper specie(s), the ligand, and a halide salt. If desired, the
m-basic salt of the hydroxy aromatic acid may, at this stage and
before the acidification in step (d), be separated from the mixture
[as optional step (c)], and may be used as an m-basic salt in
another reaction or for other purposes.
[0029] The m-basic salt of the hydroxy aromatic acid is then
contacted in step (d) with acid to convert it to the hydroxy
aromatic acid product. Any acid of sufficient strength to protonate
the m-basic salt is suitable. Examples include without limitation
hydrochloric acid, sulfuric acid and phosphoric acid.
[0030] The reaction temperature for steps (a) and (b) is preferably
between about 60 and about 120.degree. C., more preferably between
about 75 and about 95.degree. C.; and the process thus in various
embodiments involves a step of heating the reaction mixture. The
solution is typically allowed to cool before the acidification in
step (d) is carried out. In various embodiments, oxygen may be
excluded during the reaction.
[0031] The copper source is copper metal ["Cu(0)"], one or more
copper compounds, or a mixture of copper metal and one or more
copper compounds. The copper compound may be a Cu(I) salt, a Cu(II)
salt, or mixtures thereof. Examples include without limitation
CuCl, CuBr, CuI, Cu.sub.2SO.sub.4, CuNO.sub.3, CuCl.sub.2,
CuBr.sub.2, CuI.sub.2, CuSO.sub.4, and Cu(NO.sub.3).sub.2. The
selection of the copper source may be made in relation to the
identity of the halogenated aromatic acid used. For example, if the
starting halogenated aromatic acid is a bromobenzoic acid, CuCl,
CuBr, CuI, Cu.sub.2SO.sub.4, CuNO.sub.3, CuCl.sub.2, CuBr.sub.2,
CuI.sub.2, CuSO.sub.4, and Cu(NO.sub.3).sub.2 will be included
among the useful choices. If the starting halogenated aromatic acid
is a chlorobenzoic acid, CuBr, CuI, CuBr.sub.2 and CuI.sub.2 will
be included among the useful choices. CuBr and CuBr.sub.2 are in
general preferred choices for most systems. The amount of copper
used is typically about 0.1 to about 5 mol% based on moles of
halogenated aromatic acid.
[0032] When the copper source is Cu(0), Cu(0), copper bromide and a
ligand may be combined in the presence of air. In the case of Cu(0)
or Cu(I), a predetermined amount of metal and ligand may be
combined in water, and the resulting mixture may be reacted with
air or dilute oxygen until a colored solution is formed. The
resulting metal/ligand solution is added to the reaction mixture
containing the m-basic salt of the halogenated aromatic acid and
base in water.
[0033] The ligand may be a Schiff base. The term "Schiff base" as
used herein denotes a functional group or type of chemical compound
containing a carbon-nitrogen double bond with the nitrogen atom
connected to an aryl group or an alkyl group but not to hydrogen,
such as shown in Formula IV. It is typically the condensation
product of a primary amine and a ketone or aldehyde, produced by a
reaction scheme such as the following:
##STR00027##
wherein R.sup.1, R.sup.2 and R.sup.3 are each independently
selected from substituted and unsubstituted C.sub.1-C.sub.16
n-alkyl, iso-alkyl and tertiary alkyl groups; and substituted and
unsubstituted C.sub.6-C.sub.30 aryl and heteroaryl groups.
[0034] In one embodiment, a Schiff base suitable for use herein as
the ligand includes a diimine such as described generally by
Formula V
##STR00028##
wherein A is selected from the group consisting of
##STR00029##
R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently
selected from substituted and unsubstituted C.sub.1-C.sub.16
n-alkyl, iso-alkyl and tertiary alkyl groups; and substituted and
unsubstituted C.sub.6-C.sub.30 aryl and heteroaryl groups;
[0035] R.sup.5 is selected from H, substituted and unsubstituted
C.sub.1-C.sub.16 n-alkyl, iso-alkyl and tertiary alkyl groups; and
substituted and unsubstituted C.sub.6-C.sub.30 aryl and heteroaryl
groups; and halogen;
[0036] R.sup.6, R.sup.7, R.sup.8 and R.sup.9 are each independently
selected from H or a substituted or unsubstituted C.sub.1-C.sub.16
n-alkyl, iso-alkyl or tertiary alkyl group; and
n=0 or 1.
[0037] The term "unsubstituted", as used with reference to an alkyl
or aryl group in a Schiff base as described above, means that the
alkyl or aryl group contains no atoms other than carbon and
hydrogen. In a substituted alkyl or aryl group, however, one or
more O or S atoms may optionally be substituted for any one or more
of the in-chain or in-ring carbon atoms, provided that the
resulting structure contains no --O--O-- or --S--S-- moieties, and
provided that no carbon atom is bonded to more than one
heteroatom.
[0038] In another embodiment, a suitable diimine for use herein as
the ligand includes N,N'-dimesityl-2,3-diiminobutane (such as
described generally by Formula VI)
##STR00030##
In this instance, n=0, R.sup.1.dbd.R.sup.2=mesityl, and R.sup.3 and
R.sup.4 are taken together to form the CH.sub.3--C--C--CH.sub.3
moiety bonded to the two nitrogen atoms.
[0039] In a further embodiment, a diimine suitable for use herein
as the ligand includes
N,N'-di(trifluoromethylbenzene)-2,3-diiminoethane (such as
described generally by Formula VII)
##STR00031##
In this instance, n=0, R.sup.1.dbd.R.sup.2=(trifluoromethyl)benzyl,
and R.sup.3 and R.sup.4 are taken together to form the
CH.sub.3--C--C--CH.sub.3 moiety bonded to the two nitrogen
atoms.
[0040] A ligand suitable for use herein may be selected as any one
or more or all of the members of the whole population of ligands
described by name or structure above. A suitable ligand may,
however, also be selected as any one or more or all of the members
of a subgroup of the whole population, where the subgroup may be
any size (1, 2, 6, 10 or 20, for example), and where the subgroup
is formed by omitting any one or more of the members of the whole
population as described above. As a result, the ligand may in such
instance not only be selected as one or more or all of the members
of any subgroup of any size that may be formed from the whole
population of ligands as described above, but the ligand may also
be selected in the absence of the members that have been omitted
from the whole population to form the subgroup.
[0041] In various embodiments, the ligand may be provided in an
amount of about 1 to about 10, preferably about 1 to about 2, molar
equivalents of ligand per mole of copper. As used herein, the term
"molar equivalent" indicates the number of moles of ligand that
will interact with one mole of copper.
[0042] When the halogenated aromatic acid is a brominated aromatic
acid, the copper source may be Cu(0) and/or a Cu(I) salt, and it
may be combined with the ligand in the presence of oxygen in water,
or a solvent mixture containing water. Alternatively, when the
Cu(I) salt is CuBr, and the ligand is one of the Schiff bases
described specifically above [such as
N,N'-dimesityl-2,3-diiminobutane or
N,N'-di(trifluoromethylbenzene)-2,3-diiminoethane], the ligand may
be provided in an amount of two molar equivalents per mole of
copper, and the CuBr may be combined with the ligand in the
presence of water and air.
[0043] The ligand is believed to facilitate the action of the
copper source as a catalyst, and/or the copper source and the
ligand are believed to function together to act as a catalyst, to
improve one or more attributes of the reaction.
[0044] The process described above also allows for effective and
efficient synthesis of related compounds, such as n-alkoxy aromatic
acids, which may be described generally by the structure of Formula
VI:
##STR00032##
wherein Ar, m and n are described as set forth above, and each
R.sup.9 is independently a substituted or unsubstituted C.sub.1-10
alkyl group. An R.sup.9 is, when unsubstituted, a univalent group
containing only carbon and hydrogen. In any such alkyl group,
however, one or more O or S atoms may optionally be substituted for
any one or more of the in-chain carbon atoms, provided that the
resulting structure contains no --O--O-- or --S--S-- moieties, and
provided that no carbon atom is bonded to more than one
heteroatom.
[0045] An n-hydroxy aromatic acid, as prepared by the process of
this invention, may be converted to an n-alkoxy aromatic acid, and
such conversion may be accomplished, for example, by contacting the
hydroxy aromatic acid under basic conditions with an n-alkyl
sulfate of the formula (R.sup.9).sub.nSO.sub.4. One suitable method
of running such a conversion reaction is as described in Austrian
Patent No. 265,244. Suitable basic conditions for such conversion
are a solution pH of at least about 8, or at least about 9, or at
least about 10, and preferably about 9 to about 11, using one or
more bases such as described above.
[0046] In certain embodiments, it may be desired to separate the
n-hydroxy aromatic acid from the reaction mixture in which it was
formed before converting it to an n-alkoxy aromatic acid.
[0047] The process described above also allows for effective and
efficient synthesis of products made from the resulting
2,5-dihydroxyterephthalic acid or 2,5-dialkoxyterephthalic acid
such as a compound, a monomer, or an oligomer or polymer thereof.
These produced materials may have one or more of ester
functionality, ether functionality, amide functionality, imide
functionality, imidazole functionality, carbonate functionality,
acrylate functionality, epoxide functionality, urethane
functionality, acetal functionality, and anhydride
functionality.
[0048] Representative reactions involving a material made by the
process of this invention, or a derivative of such material,
include, for example, making a polyester from a
2,5-dihydroxyterephthalic acid and either diethylene glycol or
triethylene glycol in the presence of 0.1% of
ZN.sub.3(BO.sub.3).sub.2 in 1-methylnaphthalene under nitrogen, as
disclosed in U.S. Pat. No. 3,047,536 (which is incorporated in its
entirety as a part hereof for all purposes). Similarly, a
2,5-dihydroxyterephthalic acid is disclosed as suitable for
copolymeriztion with a dibasic acid and a glycol to prepare a
heat-stabilized polyester in U.S. Pat. No. 3,227,680 (which is
incorporated in its entirety as a part hereof for all purposes),
wherein representative conditions involve forming a prepolymer in
the presence of titanium tetraisopropoxide in butanol at
200-250.degree. C., followed by solid-phase polymerization at
280.degree. C. at a pressure of 0.08 mm Hg.
[0049] A 2,5-dihydroxyterephthalic acid has also been polymerized
with the trihydrochloride-monohydrate of tetraaminopyridine in
strong polyphosphoric acid under slow heating above 100.degree. C.
up to about 180.degree. C. under reduced pressure, followed by
precipitation in water, as disclosed in U.S. Pat. No. 5,674,969
(which is incorporated in its entirety as a part hereof for all
purposes); or by mixing the monomers at a temperature from about
50.degree. C. to about 110.degree. C., and then 145.degree. C. to
form an oligomer, and then reacting the oligomer at a temperature
of about 160.degree. C. to about 250.degree. C. as disclosed in
U.S. Provisional Application No. 60/665,737, filed Mar. 28, 2005
(which is incorporated in its entirety as a part hereof for all
purposes), published as WO 2006/104974. The polymer that may be so
produced may be a
pyridobisimidazole-2,6-diyl(2,5-dihydroxy-p-phenylene)polymer such
as a poly(l,4-(2,5-dihydroxy) phenylene-2,6-pyrido[2,3-d:
5,6-d']bisimidazole)polymer, or a
poly[(1,4-dihydrodiimidazo[4,5-b:4',5'-e]pyridine-2,6-diyl)
(2,5-dihydroxy-1,4-phenylene)]polymer. The pyridobisimidazole
portion thereof may, however, be replaced by any or more of a
benzobisimidazole, benzobisthiazole, benzobisoxazole,
pyridobisthiazole and a pyridobisoxazole; and the
2,5-dihydroxy-p-phenylene portion thereof may be replace the
derivative of one or more of isophthalic acid, terephthalic acid,
2,5-pyridine dicarboxylic acid, 2,6-naphthalene dicarboxylic acid,
4,4'-diphenyl dicarboxylic acid, 2,6-quinoline dicarboxylic acid,
and 2,6-bis(4-carboxyphenyl)pyridobisimidazole.
EXAMPLES
[0050] The present invention is further defined in the following
examples. It should be understood that these examples, while
indicating preferred embodiments of the invention, are given by way
of illustration only. From the above discussion and these examples,
one skilled in the art can ascertain the essential characteristics
of this invention, and without departing from the spirit and scope
thereof, can make various changes and modifications of the
invention to adapt it to various uses and conditions.
[0051] Materials: The following materials were used in the
examples. All reagents were used as received. Product purity was
determined by .sup.1H NMR.
[0052] The N,N'-dimesityl-2,3-diiminobutane was made following the
procedure in Journal of the American Chemical Society (2002), 124
(7) 1378-1399. The 2,5-dibromoterephthalic acid (95+% purity) was
obtained from Maybridge Chemical Company Ltd. (Cornwall, United
Kingdom ).
[0053] The 2-aminobenzotrifluoride [also known as
"2-(trifluoromethyl)aniline"] (99% purity, catalog number A4,160-7)
and 2,3-butandione (97% purity, catalog number B8,530-7) were
obtained from the Aldrich Chemical Company (Milwaukee, Wis.,
USA).
[0054] Copper(I) bromide ("CuBr") (98% purity) was obtained from
Acros Organics (Geel, Belgium). Na.sub.2CO.sub.3 (99.5% purity) was
obtained from EM Science (Gibbstown, N.J.).
[0055] As used herein, the term "conversion" denotes to how much
reactant was used up as a fraction or percentage of the theoretical
amount. As used herein, the term "selectivity" for a product P
denotes the molar fraction or molar percentage of P in the final
product mix. The conversion times the selectivity thus equals the
maximum "yield" of P; the actual or "net" yield will normally be
somewhat less than this because of sample losses incurred in the
course of activities such as isolating, handling, drying, and the
like. As used herein, the term "purity" denotes what percentage of
the in-hand, isolated sample is actually the specified
substance.
[0056] The terms "H.sub.2O" and "water" as used in the Examples
refer to distilled water. The meaning of abbreviations is as
follows: "h" means hour(s), "min" means minute(s), "mL" means
milliliter(s), "g" means gram(s), "mg" means milligram(s), "mol"
means mole(s), "mol equiv" means molar equivalent(s), "mmol" means
millimole(s), "D" means density, "IR" means infrared spectroscopy,
and "NMR" means nuclear magnetic resonance spectroscopy.
Example 1
[0057] This example demonstrates the formation of
2,5-dihydroxyterephthalic acid from 2,5-dibromoterephthalic acid
using CuBr and N,N'-dimesityl-2,3-diiminobutane
##STR00033##
[0058] Under nitrogen, 2.00 g (6.2 mmol) of
2,5-dibromooterephthalic acid were combined with 10 g of H.sub.2O,
0.679 g (6.4 mmol) of Na.sub.2CO.sub.3 was then added. The mixture
was heated to reflux with stirring for 30 min, remaining under a
nitrogen atmosphere. Another 0.950 g (9.0 mmol) of Na.sub.2CO.sub.3
was added to the reaction mixture and reflux was continued for 30
min. Separately, 9 mg (0.01 mol equiv) of CuBr and 40 mg (0.02 mol
equiv) of N,N'-dimesityl-2,3-diiminobutane were combined with 2 mL
H.sub.2O under nitrogen. The resulting mixture was stirred under an
air atmosphere until the CuBr was dissolved. This solution was
added to the stirred reaction mixture via syringe at 80.degree. C.
under nitrogen and stirred for 30 h at 80.degree. C. After cooling
to 25.degree. C., the reaction mixture was acidified with HCl
(conc.), producing a dark yellow precipitate. The yellow
precipitate was filtered and washed with water. After drying, a
total of 1.09 g of crude 2,5-dihydroxyterephthalic acid was
collected. The purity of 2,5-dihydroxyterephthalic acid was
determined by .sup.1H NMR to be about 81%. The net yield of
2,5-dihydroxyterephthalic acid was determined to be 72%.
Example 2
[0059] Under nitrogen, 2.01 g (10 mmol) of 2-bromobenzoic acid was
combined with 10 g of H.sub.2O. 1.32 g (12.5 mmol) of
Na.sub.2CO.sub.3 was then added. The mixture was heated to reflux
with stirring for 60 min, remaining under a nitrogen atmosphere.
Separately, 28 mg (0.0125 mol equiv) of CuBr.sub.2 and 80 mg (0.025
mol equiv) of N,N'-dimesityl-2,3-diiminobutane were combined under
nitrogen, followed by addition of 2 mL H.sub.2O under air. This
solution was added to the stirred reaction mixture via syringe at
80.degree. C. under nitrogen and stirred for 7 h at 80.degree. C.
After cooling to 25.degree. C., the reaction mixture was acidified
with HCl (conc.), producing an off-white precipitate. The
precipitate was filtered and washed with water and dried. Both the
conversion and selectivity of salicylic acid were determined to be
97% by .sup.1H NMR. The net yield was determined to be 94%.
Example 3
[0060] N,N'-di(trifluoromethylbenzene)-2,3-diiminoethane was
prepared as follows: a mixture of 10.2 mL (13.1 g; 81.2 mmol;
D=1.28) 2-aminobenzotrifluoride and 3.6 mL (3.5 g; 41 mmol; D=0.98)
freshly-distilled 2,3-butandione in 15 mL methanol containing 6
drops of 98% formic acid was stirred at 35.degree. C. under
nitrogen for 8 days. A rotovap was used to remove solvent from the
reaction mixture, and the resultant crystalline solids (1.3 g) were
washed with carbon tetrachloride. The crystals were dissolved in
chloroform; the solution was passed through a short alumina column
and evaporated to yield 1.0 g of yellow crystals of the diimine.
.sup.1H NMR (CDCl.sub.3): 2.12 ppm (s, 6H, CH3); 6.77 (d, 2H, ArH,
J=9 Hz); 7.20 (t, 2H, ArH, J=7 Hz); 7.53 (t, 2H, ArH, J=7 Hz); 7.68
(t, 2H, ArH, J=8 Hz). IR: 1706, 1651, 1603, 1579, 1319, 111
cm.sup.-1. Melting point: 154-156.degree. C.
##STR00034##
[0061] Under nitrogen, 2.01 g (10 mmol) of 2-bromobenzoic acid was
combined with 10 g of H.sub.2O; 1.32 g (12.5 mmol) of
Na.sub.2CO.sub.3 was then added. The mixture was heated to reflux
with stirring for 60 min, remaining under a nitrogen atmosphere.
Separately, 22 mg (0.01 mol equiv) of CuBr.sub.2 and 80 mg (0.02
mol equiv) of N,N'-di(trifluoromethylbenzene)-2,3-diiminoethane
were combined under nitrogen, followed by addition of 2 mL H.sub.2O
under air. This solution was added to the stirred reaction mixture
via syringe at with 80.degree. C. under nitrogen and stirred for 72
h at 80.degree. C. After cooling to 25.degree. C., the reaction
mixture was acidified with HCl (conc.), producing an off-white
precipitate. The precipitate was filtered and washed with water and
dried. The conversion and selectivity of salicylic acid were
determined to be 94% and 96%, respectively, by .sup.1H NMR. The net
yield was determined to be 90%.
[0062] Where a process of this invention is stated or described as
comprising, including, containing, having, being composed of or
being constituted by certain steps, it is to be understood, unless
the statement or description explicitly provides to the contrary,
that one or more steps in addition to those explicitly stated or
described may be present in the composition. In an alternative
embodiment, however, a process of this invention may be stated or
described as consisting essentially of certain steps, in which
embodiment steps that would materially alter the principle of
operation or the distinguishing characteristics of the process are
not present therein. In a further alternative embodiment, a process
of this invention may be stated or described as consisting of
certain steps, in which embodiment steps other than those
specifically stated or described are not present therein.
[0063] Where an embodiment of this invention is stated or described
as comprising, including, containing, having, being composed of or
being constituted by certain features, it is to be understood,
unless the statement or description explicitly provides to the
contrary, that one or more features in addition to those explicitly
stated or described may be present in the embodiment. An
alternative embodiment of this invention, however, may be stated or
described as consisting essentially of certain features, in which
embodiment features that would materially alter the principle of
operation or the distinguishing characteristics of the embodiment
are not present therein. A further alternative embodiment of this
invention may be stated or described as consisting of certain
features, in which embodiment, or in insubstantial variations
thereof, only the features specifically stated or described are
present.
[0064] Where the indefinite article "a" or "an" is used with
respect to a statement or description of the presence of a step in
a process of this invention, it is to be understood, unless the
statement or description explicitly provides to the contrary, that
the use of such indefinite article does not limit the presence of
the step in the process to one in number.
[0065] Where a range of numerical values is recited herein, unless
otherwise stated, the range is intended to include the endpoints
thereof, and all integers and fractions within the range. It is not
intended that the scope of the invention be limited to the specific
values recited when defining a range.
* * * * *