U.S. patent application number 14/370699 was filed with the patent office on 2015-01-15 for processes for isolating fluorinated products.
This patent application is currently assigned to UBE Industries, Ltd.. The applicant listed for this patent is UBE Industries, Ltd.. Invention is credited to Junichi Chika, Norimichi Saito, Teruo Umemoto.
Application Number | 20150018587 14/370699 |
Document ID | / |
Family ID | 47884456 |
Filed Date | 2015-01-15 |
United States Patent
Application |
20150018587 |
Kind Code |
A1 |
Saito; Norimichi ; et
al. |
January 15, 2015 |
PROCESSES FOR ISOLATING FLUORINATED PRODUCTS
Abstract
Useful processes for isolating the fluorinated products formed
by reaction with 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride
(Fluolead) are disclosed. The processes comprise the conversion of
the byproduct (formula I) to sulfinate ester (formula V), and to
sulfonate eater (formula VI), and then to the water-soluble
sulfonate salt (formula IV) in the presence of the fluorinated
products.
Inventors: |
Saito; Norimichi; (Denver,
CO) ; Chika; Junichi; (Denver, CO) ; Umemoto;
Teruo; (Denver, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UBE Industries, Ltd. |
Yamaguchi |
|
JP |
|
|
Assignee: |
UBE Industries, Ltd.
Yamaguchi
JP
|
Family ID: |
47884456 |
Appl. No.: |
14/370699 |
Filed: |
February 7, 2013 |
PCT Filed: |
February 7, 2013 |
PCT NO: |
PCT/JP2013/053595 |
371 Date: |
July 3, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61597056 |
Feb 9, 2012 |
|
|
|
Current U.S.
Class: |
570/177 |
Current CPC
Class: |
C07C 2603/18 20170501;
C07C 303/32 20130101; C07C 17/18 20130101; C07C 17/395 20130101;
C07C 313/04 20130101; C07C 17/18 20130101; C07C 303/32 20130101;
C07C 17/395 20130101; C07C 303/26 20130101; C07C 25/22 20130101;
C07B 63/00 20130101; C07C 309/73 20130101; C07C 309/31 20130101;
C07C 303/26 20130101; C07C 25/22 20130101 |
Class at
Publication: |
570/177 |
International
Class: |
C07C 17/395 20060101
C07C017/395 |
Claims
1. A method for isolating a fluorinated product from a byproduct
where the fluorinated product results from fluorination with
4-tert-butyl-2,6-dimethylphenylsulfur trifluoride: the method
comprising: in the presence of the fluorinated product, converting
the byproduct having a formula (I) to a sulfinate ester having a
formula (V), and then to a sulfonate ester having a formula (VI),
and then to a sulfonate salt having a formula (IV); ##STR00007## in
which: R is alkyl group having 1 to 4 carbon atoms and M is a
hydrogen atom, a metal atom or an ammonium moiety; and wherein the
fluorinated product is isolated from the byproduct by utilizing
physical property differences between the byproduct and sulfonate
salt.
2. The method of claim 1 which comprises: a first step of treating
a mixture including the fluorinated product and the byproduct (I)
with an alcohol to convert (I) to sulfinate ester (V); a second
step of treating a mixture including the fluorinated product and
the sulfinate ester (V) obtained in the first step with an oxidizer
to convert (V) to sulfonate ester (VI): and a third step of
treating a mixture including the fluorinated product and the
sulfonate ester (VI) obtained in the second step with a nucleophile
to convert (VI) to sulfonate salt (IV).
3. The method of claim 2 wherein the alcohol is selected from a
group consisting of methanol, ethanol, propanol, isopropanol,
butanol, sec-butanol, isobutanol, and tert-butanol.
4. The method of claim 2 wherein the oxidizer is selected from a
group consisting of hydrogen peroxide and peracetic acid.
5. The method of claim 2 wherein a nucleophile is potassium
hydroxide.
Description
TECHNICAL FIELD
[0001] The invention relates to processes for isolation of
fluorinated products from byproducts where the fluorination
products are prepared using 4-tert-butyl-2,6-dimethylphenylsulfur
trifluoride (Fluolead).
BACKGROUND ART
[0002] The present invention relates to processes for isolating
fluorinated products in fluorination reactions that utilize
4-tert-butyl-2,6-dimethylphenylsulfur trifluorides (Fluolead).
Fluolead has recently been developed as a very useful
deoxofluorinating agent with high thermal stability, ease of
handling, unusual resistance to aqueous hydrolysis, and wide
application [see, for example, J. Am. Chem. Soc., 2010, 132,
18199-18205 and its supporting information]. Fluolead's excellent
and unique properties are based on extremely high lipophilicity
caused by a tert-butyl and two methyl substituents on a benzene
ring. Fluolead fluorinates many kinds of organic compounds such as
alcohols, aldehydes, ketones, carboxylic acids, thioketones,
thioesters, dithioesters, thiocarbonate, and dithiocarbonates to
give the corresponding fluorinated compounds in high yields. These
fluorinated compounds are useful for the preparation or development
of medicines, agrochemicals, liquid crystals, and the like (see,
for example, J. Fluorine Chem. 2006, Vol. 127, pp. 992-1012; Chem.
& Eng. News, June 5, pp. 15-32 (2006); "Modern Fluoroorganic
Chemistry--Synthesis, Reactivity, Applications" , Wily-VCH,
Weinheim (2004), pp. 203-277; Angew. Chem. Ind. Ed., Vol. 39, pp.
4216-4235 (2000)). Therefore, Fluolead has high potential to apply
to these industries due to its high fluorination capability.
[0003] However, there is a drawback in fluorination reactions using
Fluolead. Fluolead reacts with an organic compound to form an
equimolar amount of a byproduct,
4-tert-butyl-2,6-dimethylphenylsulfinyl fluoride (represented by
compound (I)), along with the fluorinated product. The byproduct is
difficult to separate from the fluorinated product and results in a
loss of product purity and therefore product effectiveness (see
equation 1 for reaction overview).
##STR00001##
[0004] The byproduct (I) cannot be removed from the organic layer
of the reaction mixture by washing it with an aqueous alkaline
solution (a required step in the isolation of the fluorinated
products), because the byproduct (I) undergoes a disproportionation
reaction during hydrolysis to substantially form thiolsulfonate
(compound (III)) and sulfonate salt (compound (IV)), as shown in
the following scheme 1:
##STR00002##
[0005] Although compound (IV) is soluble in an aqueous layer,
compound (III) is not. Therefore, the fluorinated products cannot
be separated from byproduct (III). The extraordinary easy
occurrence of the disproportionation of byproduct (I) to (III) via
(II) is owing to its high lipophilicity caused by its unique
chemical structure, that is, one tert-butyl and two methyl
substituents on a benzene ring. Therefore, the fluorinated
compounds are contaminated with a significant amount of solid
thiolsulfonate (III). Column-chromatography for the separation of
compound (III) from the fluorinated products requires is relatively
costly, and is not suitable for the large scale production.
Alternatively, fractional distillation for the separation has
limited scope, because it cannot be applied to solid fluorinated
products. Therefore, the solution to producing industrial amounts
of fluorinated products using Fluolead requires a new approach.
[0006] The present invention is directed toward overcoming the
problem discussed above.
SUMMARY OF INVENTION
[0007] The present invention provides processes for effective
isolation of a fluorinated product(s) from byproducts during
fluorination reactions using 4-tert-butyl-2,6-dimethylphenylsulfur
trifluoride (Fluolead). The processes comprise converting the
byproducts of the reaction, represented by compound (I), to
water-soluble sulfonate salts, having a formula of compound (IV).
The sulfonate salts being removed from the fluorinated products via
solubility differences between the two groups of materials, i.e.,
sulfonate salts being soluble in the aqueous layer and the
fluorinated products in the organic layer. These processes are
extremely effective at removing substantially all of the byproduct
from the fluorinated product and thereby providing an unexpectedly
useful and pure fluorinated product. In alternative embodiments,
other differences in physical properties between the sulfonate
salts and fluorinated products can be used for separation, for
example, differences in their ionic and non-ionic natures.
[0008] The present invention provides methods for converting
byproduct (I) to sulfinate ester of formula (V), and then to
sulfonate ester of formula (VI), and then to sulfonate salt of
formula (IV) in the presence of a fluorinated product formed in the
fluorination with Fluolead.
[0009] The present invention also provides methods which comprise a
first step of treating a mixture of a fluorinated product and
byproduct (I) with an alcohol, a second step of treating a mixture
of the fluorinated product and sulfinate ester (V) with an
oxidizer, and a third step of treating the fluorinated product and
sulfonate ester (VI) with a nucleophile. Note that two steps (steps
one and two, or steps two and three) can also be performed at
substantially the same time. All the steps (steps one, two, and
three) may also be performed at substantially the same time.
[0010] The fluorinated product is isolated by simple processes of
the present invention that are very cost effective. This method is
quite suitable for large scale production as it is based on the
physical properties differences between the fluorinated products
and the ionic sulfonate salt compound.
[0011] These and various other features as well as advantages which
characterize the invention will be apparent from a reading of the
following detailed description and a review of the appended
claims.
DESCRIPTION OF EMBODIMENT
[0012] Embodiments of the present invention provide processes for
isolation of fluorinated products in fluorination reactions using
4-tert-butyl-2,6-dimethylphenylsulfur trifluoride (Fluolead). These
processes are useful at an industrial scale, providing fluorinated
products of high yield and high purity. The byproducts are very
effectively, safely, and at low cost removed from the fluorinated
products. The separation of substantially all byproduct from the
fluorinated product relies on the conversion of the byproduct to a
corresponding sulfonate salt. The physical differences (physical
property differences) between the neutral byproduct and the ionic
sulfonate salt are utilized to separate the salt away from the
fluorinated product (differences not present between the byproduct
and fluorinated products). In one embodiment, the physical
differences can be realized via liquid-liquid or liquid-solid
extraction principles which allow for use in industrial scale
application. Alternative embodiments can utilize absorption
characteristics of the sulfonate salt against the fluorinated
products.
[0013] The present invention provides methods comprising: in the
presence of a fluorinated product, a byproduct having a formula (I)
is converted to a water-soluble sulfonate salt having a formula
(IV).
[0014] In more detail, the present invention provides methods which
comprise converting the byproduct (I) to sulfinate ester having a
formula (V), and then to sulfonate ester having a formula (VI), and
then to the sulfonate salt having a formula (IV). The compounds
(I), (V), (VI), and (IV) are as follows:
##STR00003##
[0015] in which: R is alkyl group having 1 to 4 carbon atoms and M
is a hydrogen atom, a metal atom, or an ammonium moiety.
[0016] The present invention may include three steps for the
conversion of byproduct (I) to sulfonate salt (IV), as shown in the
following equation (Equation 2):
##STR00004##
[0017] In one embodiment, the three steps are (step 1) alcoholysis
step, (step 2) oxidation step, and (step 3) nucleophile treatment
step, and this three-steps procedure may be followed by the first
fluorination reaction of an organic compound with Fluolead (see,
Scheme 2).
##STR00005##
Step 1 in Scheme 2
[0018] Step 1 is a process for treating a mixture with alcohol. The
mixture is obtained from fluorination reaction of an organic
compound with 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride
(Fluolead) and the mixture includes a fluorinated product and
byproduct as represented by formula (I).
[0019] Fluolead is commercially available. The organic compounds
fluorinated with Fluolead are exemplified as any organic compounds
which are fluorinated with Fluolead. Typically, the organic
compounds are selected from a group consisting of alcohols,
aldehydes, ketones, diketones, keto esters, carboxylic acids,
thioketones, thioesters, dithioesters, thiocarbonates, and
dithiocarbonates. The fluorination of organic compounds with
Fluolead can be carried out according to the known reaction
procedures and conditions (see, for example, J. Am. Chem. Soc.,
2010, 132, 18199-18205 and t is supporting information,
incorporated herein by reference for all purposes).
[0020] Step 1 comprises treating the obtained mixture with an
alcohol.
[0021] The mixture used for step 1 contains a fluorinated
product(s) and byproduct (I). In addition, the mixture may contain
Fluolead and/or the non-fluorinated organic compound, which are
unreacted or overused in the fluorination process with Fluolead.
Fluolead reacts with an alcohol to quantitatively give sulfinate
ester of formula (V).
[0022] The alcohols used for this step can be selected from the
group including: methanol, ethanol, propanol, isopropanol, butanol,
isobutanol, sec-butanol, and tert-butanol. Among them, methanol and
ethanol are preferable because of their availability and cost.
[0023] Step 1 can be accomplished by adding a suitable amount of
alcohol to the reaction mixture and the resulting mixture is
stirred until byproduct (I) is completely converted to sulfinate
ester (V).
[0024] In order to get an excellent conversion of compounds
represented by formula (I) to compounds represented by formula (V),
a preferable amount of alcohol can be chosen in the range of about
1 mol to a large excess per 1 mol of the byproduct (I). About 3 mol
to about 20 mol of alcohol is more preferable per 1 mol byproduct.
The alcohol can also be used as a solvent or one of solvents for
this step (step 1). The amount of byproduct can be predicted via
the expected yield of the fluorinated products produced by Fluolead
(the byproduct is formed in at least equimolar amount to the
fluorinated product) or via objective detection standards like NMR
or the like. The amount of byproduct may be evaluated by the amount
of Fluolead that was originally used.
[0025] When unreacted or overused Fluolead is included in the
mixture, an additional amount of alcohol is needed, which reacts
with all the Fluolead to form sulfinate ester of formula (V). In
order to convert Fluolead to the sulfinate, a preferable amount of
alcohol is about 3 mol to about 20 mol per 1 mol of Fluolead. A
large excess of alcohol can also be used.
[0026] In order to get an excellent conversion of compound (I) to
compound (V), the reaction temperature is in the range of about
-20.degree. C..about.+100.degree. C. More preferably, the reaction
temperature is about 0.degree. C..about.+50.degree. C.
[0027] The reaction time can be chosen to complete the conversion.
Typically, it is within a day, and more preferable within several
hours.
[0028] The reaction of Step 1 is carried out with or without any
other solvent. Suitable solvents for use herein include, but are
not limited to, alkanes, halocarbons, aromatics, ethers, nitriles
and so on, as well as mixtures of the above. Illustrative alkanes
are normal, branched, or cyclic pentane, hexane, heptane, octane,
nonane, decane, and so on. Illustrative halocarbons are
dichloromethane, chloroform, carbon tetrachloride, dichloroethane,
trichlorotrifluoroethane, and so on. Illustrative aromatics are
benzene, toluene, xylene, chlorobenzene, fluorobenzene,
benzotrifluoride, and so on. Illustrative ethers are diethyl ether,
dipropyl ether, di(isopropyl) ether, dibutyl ether, tert-butyl
methyl ether, tetrahydrofuran, dioxane, methyl nonafluorobutyl
ether, ethyl 1,1,2,2-tetrafluoroethyl ether,
1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether, and so on.
Illustrative nitriles are acetonitrile, propionitrile,
butyronitrile, and so on. As noted above, an alcohol as a reactant
for this step can also be used as a solvent or one of solvents.
[0029] Note that because, in many cases, solvent is already in the
Fluolead reaction to produce fluorinated products, additional
solvent is often not required, i.e., the solvent from the original
reaction is present and all that needs to be added is the alcohol.
However, additional solvent can be added to the reaction, even
where the original reaction included solvent.
Step 2 in Scheme 2
[0030] Step 2 is a process of treating the reaction mixture
obtained from step 1 with an oxidizer. The reaction mixture for
step 2 includes the fluorinated product and sulfinate ester of
formula (V). The oxidizer can be selected from normal oxidizers
such as hydrogen peroxide, hydroge peroxide-urea adduct, peracetic
acid, perbenzoic acid, m-chloroperbenzoic acid, monoperoxy oxalic
acid, monoperphthalic acid, nitric acid, potassium
peroxymonosulfate (OxoneR), sodiun perchlorate, sodium perbromate,
sodium periodate, potassium periodate, sodium persulfate, potasium
permanganate, sodium perborate, sodium percarbonate, bromine,
chlorine, sodium hypochlorite, and the like.
[0031] In order to get significant conversion of compound (V) to
compound (VI), a preferable amount of an oxidizer can be chosen in
the range of about 1 mol to about 5 mol per 1 mol of the sulfinate
ester (amount of sulfinate ester evaluated by determining how much
byproduct was originally present, or how much Fluolead was
originally used, for example). About 1 mol to about 3 mol of
oxidizer is more preferable.
[0032] In order to get significant conversion of compound (V) to
compound (VI), the reaction temperature is in the range of about
-20.degree. C..about.+120.degree. C. More preferably, the reaction
temperature is about 0.degree. C..about.+100.degree. C.
[0033] The reaction time can be chosen to complete the conversion.
Typically, it is within a few days, and more preferable within a
day.
[0034] The reaction of step 2 is carried out with or without any
other solvent. The use of the solvent is preferable for mild
reaction conditions. Suitable solvents for use herein include, but
are not limited to, water, alcohols, carboxylic acids, alkanes,
halocarbons, aromatics, ethers, and so on, as well as mixtures of
the above. Illustrative alcohols include, but are not limited to,
methanol, ethanol, propanol, isopropanol, butanol, and so on.
Illustrative carboxylic acids are formic acid, acetic acid,
propionic acid, and so on. Alkanes, halocarbons, aromatics, and
ethers are exemplified as for step 1. As above the original solvent
used in step 1 can be used for step 2. Additional solvent can be
added in step 2 if necessary. Note also that the solvent used in
step 1 and used in 2 do not have to be the same, for example an
alcohol could be used in step 1 and a carboxylic acid used in step
2. Because step 2 is an oxidation reaction, solvents must allow for
the oxidation step. Addition of solvent to step 2 can be determined
for making the reaction smooth, i.e., accomplish the reaction in a
pre-set amount of time (in some instances the progress of the
reaction can be checked using gas chromatography or other like
methodologies).
Step 3 in Scheme 2
[0035] Step 3 is treating the reaction mixture obtained from step 2
with a nucleophile to convert sulfonate ester of formula (VI) to
sulfonate salt of formula (IV) which is soluble in water or
alkaline water. The reaction mixture includes the fluorinated
product and sulfonate ester of formula (VI). The nucleophiles used
in step 3 includes, are not limited to, water, hydroxides,
alkoxides, amines, halides, cyanides, and so on. Illustrative
hydroxides include lithium hydroxide, sodium hydroxide, potassium
hydroxide, and so on. Illustrative alkoxides includes lithium
methoxide, sodium methoxide, potassium methoxide, lithium ethoxide,
sodium ethoxide, potassium ethoxide, and so on. Illustrative amines
includes ammonia, methylamine, dimethylamine, ethylamine,
diethylamine, propylamine, dipropylamine, and so on. Illustrative
halides include sodium chloride, potassium chloride, sodium
bromide, potassium bromide, sodium iodide, potassium iodide, and so
on. Illustrative cyanides include sodium cyanide, potasium cyanide,
and so on. Between these sodium and potassium compounds, potassium
compounds are preferable because potassium
4-tert-butyl-2,6-dimethylphenylsulfonate (IV: M=K) is more soluble
in water than sodium 4-tert-butyl-2,6-dimethylphenylsulfonate (IV:
M=Na).
[0036] In order to get an excellent conversion of compounds
represented by formula (VI) to compounds represented by formula
(IV), a preferable amount of a nucleophile can be chosen in the
range of about 1 mol to a large excess per 1 mol of the sulfonate
ester. About 1 mol to about 10 mol of a nucleophile is
preferable.
[0037] In order to get an excellent conversion of compounds of (VI)
to compounds of (IV), the reaction temperature is in the range of
about -20.degree. C..about.+120.degree. C. More preferably, the
reaction temperature is about 0.degree. C..about.+100.degree.
C.
[0038] The reaction time can be chosen to complete the conversion.
Typically, it is within a few days, and more preferable within a
day.
[0039] The reaction of step 3 is carried out with or without any
other solvent. The use of the solvent is preferable for mild
reaction conditions and high yield reaction. Suitable solvents for
use herein include, but are not limited to, water, alcohols, ether,
and so on, as well as mixtures of the above. Illustrative alcohols
include, but are not limited to, methanol, ethanol, propanol,
isopropanol, butanol, and so on. Illustrative ethers are diethyl
ether, dipropyl ether, di(isopropyl) ether, dibutyl ether,
tert-butyl methyl ether, tetrahydrofuran, dioxane, and so on. The
solvent used for the step 2 can be used for step 3.
[0040] A distinction from processes in the prior art is that
embodiments of the invention utilize simple techniques suitable for
the large scale production of fluorinated products. These processes
can utilize, for example, liquid-liquid or liquid-solid extraction
techniques, where the sulfonate salt is separated away from the
fluorination products as shown in Scheme 2.
[0041] According to the present invention, the fluorinated products
can be isolated by means of standard simple processes which do not
require column chromatography, fine distillation purification, and
any other special performance of high technology. This is a
significant improvement in industrial application over the prior
art to isolate the fluorinated products.
[0042] The following examples will illustrate the present invention
in more detail, but it should be understood that the present
invention is not deemed to be limited thereto.
EXAMPLES
Example 1
Isolation of 2,7-dibromo-9,9-difluorofluorene formed in the
fluorination of 2,7-dibromo-9-fluorenone with Fluolead
##STR00006##
[0044] A fluoropolymer (PFA) reactor with septum/port was charged
with 13.5 g (40 mmol) of 2,7-dibromo-9-fluorenone, 21.7 g (80 mmol)
of 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride (purity 93%)
(Fluolead), 40 mL of dry toluene, and 4.0 mL of a 7:3 (wt/wt)
mixture of hydrogen fluoride and pyridine. The reactor was closed
with septum and placed in an oil bath at 77.degree. C. for 24
hrs.
[0045] (Step 1): After cooling in an ice bath, 30 mL of ethanol was
added to the reaction mixture. The ice bath was removed and
reaction mixture was stirred for 30 minutes, after which it was
poured into an aqueous solution of 40 g of sodium carbonate in 500
mL of water. The organic layer was separated and the aqueous layer
was extracted with ether. The combined organic layer was washed
with water, dried with sodiun sulfate, and filtered. The filtrate
was evaporated to give 38.93 g of a residue, which has the
fluorinated product and ethyl
4-tert-butyl-2,6-dimethylphenylsulfinate (V) (R=Et) by GC analysis
and NMR analysis. Spectral data of ethyl
4-tert-butyl-2,6-dimethylphenylsulfinate: .sup.1H NMR (CDC1.sub.3)
8 7.03 (s, 2H), 4.15 (m, 2H), 2.62 (s, 6H), 1.38 (t, J=7 Hz, 3H),
1.28 (s, 9H); GC-Mass 254 (M.sup.+).
[0046] (Step 2): The residue was then dissolved in 80 mL of acetic
acid. The mixture was heated in an oil bath at 70.degree. C. and
then 13.6 g of 30% hydrogen peroxide (H.sub.2O.sub.2, 0.12 mol) was
added in portions over 15 minutes. The mixture was stirred for
additional 2 hrs, cooled to room temperature, and then poured into
water including 16 g of sodiun sulfite. The mixture was extracted
with a mixture of toluene and ether and the organic layer was
washed with water, dried with sodium sulfate, and filtered. The
filtrate was evaporated to give 23.03 g of a residue, which has the
fluorinated compound and ethyl
4-tert-butyl-2,6-dimethylphenylsulfonate (VI) (R=Et) by GC and NMR
analysis. Spectral data of ethyl
4-tert-butyl-2,6-dimethylphenylsulfonate: .sup.1H NMR (CDCl.sub.3)
.delta.7.14 (s, 2H), 4.07 (quartet, J=7.1 Hz, 2H), 2.66 (s, 6H),
1.32 (t, J=7.1 Hz, 3H), 1.30 (s, 9H); GC-Mass 270 (M.sup.+).
[0047] (Step 3): The residue was mixed with 100 mL of ethanol and
the mixture was heated at 70.degree. C. Into the mixture, 20 mL of
10% KOH aqueous solution was added and the mixture was stirred for
2 hrs at 70.degree. C. After cooling to room temperature, the
mixture was concentrated and the resulting mixture was mixed with
water and extracted with ether. The combined organic layer was
washed with water, dried with sodium sulfate, and filtered. Solvent
of the filtrate was removed to give 16.45 g of a yellow solid
residue which is the fluorinated product by GC analysis. The GC
analysis showed the yellow solid residue did not include any of
ethyl 4-tert-butyl-2,6-dimethylphenylsulfonate. The solid residue
was triturated in 25 mL of ethanol, chilled in an ice bath, and
then filtered to give 13.3 g of the fluorinated product,
2,7-dibromo-9,9-difluorofluorene after drying. The product's yield
was 92% and purity was 100% by GC analysis.
[0048] Spectral data of 2,7-dibromo-9,9-difluorofluorene: .sup.1H
NMR (CDCl.sub.3) .delta.7.73 (broad quartet, J=1.6 Hz, 1H), 7.58
(dd, J=8.1 Hz, 0.7 Hz, 1H), 7.37 (d, J=8.1 Hz, 1H); .sup.19F NMR
(CDCl.sub.3) .delta.-110.87 (s); GC-Mass 362 (M.sup.+), 360
(M.sup.+), 358 (M.sup.+).
[0049] While a presently preferred embodiment has been described
for purposes of this disclosure, various changes and modifications
may be made which are well within the scope of the invention.
Numerous other changes may be made which will readily suggest
themselves to those skilled in the art and which are encompassed in
the spirit of the invention disclosed herein and as defined in the
appended claims. All publications cited herein are hereby
incorporated by reference.
* * * * *