U.S. patent application number 09/769797 was filed with the patent office on 2001-08-16 for process for the preparation of 3,5-bis(trifluoro-methyl)-benzoyl chlorides and novel 3,5-bis(tri-halogenomethyl)-and 3,5-dimethylbenzoyl halides.
Invention is credited to Marhold, Albrecht, Stolting, Jorn.
Application Number | 20010014759 09/769797 |
Document ID | / |
Family ID | 7629689 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010014759 |
Kind Code |
A1 |
Marhold, Albrecht ; et
al. |
August 16, 2001 |
Process for the preparation of 3,5-bis(trifluoro-methyl)-benzoyl
chlorides and novel 3,5-bis(tri-halogenomethyl)-and
3,5-dimethylbenzoyl halides
Abstract
3,5-Bis(trifluoromethyl)benzoyl chlorides optionally substituted
with fluorine or chlorine are advantageously prepared by converting
3,5-dimethylbenzoic acids optionally substituted with fluorine or
chlorine into the corresponding acid chlorides; completely
free-radically chlorinating said chlorides in the side chains,
giving 3,5-bis(trichloromethyl)benzoyl chlorides optionally
substituted by fluorine or chlorine; fluorinating the latter with
anhydrous hydrogen fluoride and/or antimony pentafluoride, giving
3,5-bis(trifluoromethyl)be- nzoyl fluorides optionally substituted
with fluorine or chlorine; and then reacting the
3,5-bis(trifluoromethyl)benzoyl fluorides with silicon
tetrachloride in the presence of a further Lewis acid. Some of the
3,5-bis(trihalogenomethyl) and 3,5-dimethylbenzoyl halides which
arise as intermediates are novel compounds.
Inventors: |
Marhold, Albrecht;
(Leverkusen, DE) ; Stolting, Jorn; (Koln,
DE) |
Correspondence
Address: |
BAYER CORPORATION
PATENT DEPARTMENT
100 BAYER ROAD
PITTSBURGH
PA
15205
US
|
Family ID: |
7629689 |
Appl. No.: |
09/769797 |
Filed: |
January 25, 2001 |
Current U.S.
Class: |
562/840 ;
562/856; 562/857 |
Current CPC
Class: |
C07C 51/60 20130101;
C07C 51/62 20130101; C07C 51/60 20130101; C07C 63/70 20130101; C07C
51/62 20130101; C07C 63/72 20130101; C07C 51/62 20130101; C07C
63/70 20130101 |
Class at
Publication: |
562/840 ;
562/857; 562/856 |
International
Class: |
C07C 051/58; C07C
053/38; C07C 055/36; C07C 057/64; C07C 059/00; C07C 061/00; C07C
062/00; C07C 063/00; C07C 065/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 3, 2000 |
DE |
10004717.3 |
Claims
What is claimed is:
1. A process for the preparation of 3,5-bis(trifluoromethyl)benzoyl
chlorides of formula (I) 10wherein X is hydrogen, fluorine, or
chlorine, comprising (1) converting 3,5-dimethylbenzoic acids of
formula (V) 11wherein X has the meaning given for formula (I), into
the corresponding acid chlorides of formula (IV) 12wherein X has
the meaning given for formula (I), (2) completely free-radically
chlorinating the acid chlorides of formula (IV) in the side chains
to give 3,5-bis(trichloromethyl)benzoyl chlorides of formula (III)
13wherein X has the meaning given for formula (I), (3) fluorinating
the 3,5-bis(trichloromethyl)benzoyl chlorides of formula (III) with
anhydrous hydrogen fluoride and/or antimony pentafluoride to give
3,5-bis(trifluoromethyl)benzoyl fluorides of formula (II) 14wherein
X has the meaning given for formula (I), and (4) reacting the
3,5-bis(trifluoromethyl)benzoyl fluorides of formula (II) with
silicon tetrachloride in the presence of a further Lewis acid to
give the compounds of the formula (I).
2. A process according to claim 1 wherein the conversion to the
acid chlorides of formula (IV) is carried out with a chlorinating
reagent selected from the group consisting of thionyl chloride,
phosphorus trichloride, phosphorus pentachloride, phosphorus
oxychloride, oxalyl chloride, and phosgene, and in the presence of
the diluent.
3. A process according to claim 1 wherein 1.1 to 10 mol of
chlorinating reagent, per mole of the benzoic acid of the formula
(V), are used and wherein the operating temperature is 0 to
150.degree. C.
4. A process according to claim 1 wherein the free-radical
side-chain chlorination is carried out at elevated temperature with
elemental chlorine using irradiation by a light source and/or the
addition of a free-radical initiator at 80 to 250.degree. C.
5. A process according to claim 1 wherein 7.2 to 12 mol of chlorine
gas are used per mole of dimethylbenzoyl chloride of the formula
(IV).
6. A process according to claim 1 wherein the fluorination is
carried out using 7.7 to 21 mol of anhydrous hydrogen fluoride per
mole of benzoyl chloride of the formula (III) with the addition of
a Lewis acid.
7. A process according to claim 1 wherein the reaction with silicon
tetrachloride is carried out in the presence of aluminum chloride,
boron trifluoride, titanium tetrachloride, iron trichloride, or
mixtures thereof.
8. A process according to claim I wherein the reaction with silicon
tetrachloride is carried out with 0.25 to 1 mol of silicon
tetrachloride and 0.01 to 0.1 mol of further Lewis acid, in each
case based on 1 mol of benzoyl fluoride of the formula (II).
9. 3,5-Bis(trifluoromethyl)benzoyl chlorides of the formula (Ia)
15wherein X' is fluorine or chlorine.
10. 3,5-Bis(trifluoromethyl)benzoyl fluorides of the formula (IIa)
16wherein X' is fluorine or chlorine.
11. 3,5-Bis(trichloromethyl)benzoyl chlorides of the formula (IIIa)
17wherein X' is fluorine or chlorine.
12. 3,5-Dimethylbenzoyl chlorides of the formula (IVa) 18wherein X'
is fluorine or chlorine.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a process for the
preparation of 3,5-bis-(trifluoromethyl)benzoyl chlorides from the
corresponding 3,5-dimethylbenzoic acids and to novel
3,5-bis(trihalogenomethyl)- and 3,5-dimethylbenzoyl halides that
arise as intermediates in the process. In the text below,
3,5-bis(trifluoromethyl)benzoyl chlorides are also referred to as
BTBs.
[0002] BTBs are intermediates for the preparation of pharmaceutical
and agrochemical active ingredients and photoresist
compositions.
[0003] The preparation of BTBs from the corresponding
3,5-bis(trifluoromethyl)benzoic acid by chlorination is known (see,
for example, J. Med. Chem., 38, 3106 (1995)). This acid can be
obtained in two different ways, by
[0004] (a) metallizing 1-bromo-3,5-bis(trifluoromethyl)benzene with
magnesium or lithium (see Bull. Soc. Chim. Fr., 1962 (587) and
Chem. Ber., 129, 233 (1996)) and then reacting with carbon dioxide
or, in the presence of a palladium catalyst, with carbon monoxide
and water (see JP-OS 09/67,297) or
[0005] (b) reacting 3,5-bis(trifluoromethyl)benzene with a mixture
of butyllithium and potassium t-butoxide (see Synlett, 1990, 747)
or only with butyllithium (see J. Organomet. Chem., 67, 321 (1974))
and then with carbon dioxide.
[0006] These processes for the preparation of BTBs are less
suitable for the industrial scale because in all cases
organometallic compounds have to be prepared and handled, which is
possible only with great technological expenditure. Moreover,
3,5-bis(trifluoromethyl)benzene and the corresponding 1-bromo
compound can be prepared only by a complex route. Added to this is
the danger of the exothermic decomposition of
meta-trifluoromethyl-substituted phenyl-magnesium and -lithium
compounds, which likewise require great expenditure for somewhat
reliable control.
[0007] It is also known that 3,5-bis(trifluoromethyl)benzoyl
fluorides can be prepared by selectively hydrolyzing
1,3,5-tris(trichloromethyl)benzene- s with water to give
3,5-bis(trichloromethyl)benzoyl chlorides (see German Patent
Specification 705,650) and then carrying out a complete chlorine/
fluorine exchange with hydrogen fluoride or antimony trifluoride
(see German Patent Specification 707,955). Whether and, where
appropriate, how the corresponding benzoyl chlorides ("BTBs") can
be obtained from 3,5-bis-(trifluoromethyl)-benzoyl fluorides is not
known.
[0008] There is therefore a need for a process for the preparation
of BTBs that can be reliably carried out on an industrial scale
without particular complexity and that starts from readily
accessible starting materials.
SUMMARY OF THE INVENTION
[0009] We have now found a process for the preparation of
3,5-bis(trifluoromethyl)benzoyl chlorides of formula (I) 1
[0010] wherein
[0011] X is hydrogen, fluorine, or chlorine, comprising
[0012] (1) converting 3,5-dimethylbenzoic acids of formula (V)
2
[0013] wherein
[0014] X has the meaning given for formula (I),
[0015] into the corresponding acid chlorides of formula (IV) 3
[0016] wherein
[0017] X has the meaning given for formula (I),
[0018] (2) completely free-radically chlorinating the acid
chlorides of formula (IV) in the side chains to give
3,5-bis(trichloromethyl)benzoyl chlorides of formula (III) 4
[0019] wherein
[0020] X has the meaning given for formula (I),
[0021] (3) fluorinating the 3,5-bis(trichloromethyl)benzoyl
chlorides of formula (III) with anhydrous hydrogen fluoride and/or
antimony pentafluoride to give 3,5-bis(trifluoromethyl)benzoyl
fluorides of formula (II) 5
[0022] wherein
[0023] X has the meaning given for formula (I), and
[0024] (4) reacting the 3,5-bis(trifluoromethyl)benzoyl fluorides
of formula (II) with silicon tetrachloride in the presence of a
further Lewis acid to give the compounds of formula (I).
[0025] In formulas (I) to (V), X is preferably hydrogen.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The first stage of the process according to the invention,
the preparation of the acid chlorides of the formula (IV) from the
benzoic acids (V), can be carried out analogously to known
processes for the preparation of carbonyl chlorides from carboxylic
acids. One possibility for the reaction of 3,5-dimethylbenzoic acid
with phosphorus pentachloride is known from Can. J. Chem., 41, 2962
(1963) and another with thionyl chloride is known from J. Org.
Chem., 24, 1301 (1959). These reactions can be carried out
analogously for compounds in which X is fluorine or chlorine. The
benzoic acids of the formula (V) required to carry out the first
stage can be prepared by known processes or analogously thereto.
3,5-Dimethylbenzoic acid is commercially available.
[0027] The conversion to the acid halides of the formula (IV) can
be carried out with chlorinating reagents, for example, with
thionyl chloride, phosphorus trichloride, phosphorus pentachloride,
phosphorus oxychloride, oxalyl chloride or phosgene. Preference is
given to using thionyl chloride or oxalyl chloride, the reaction
products of which (hydrogen chloride and sulfur dioxide or hydrogen
chloride, carbon monoxide and carbon dioxide respectively) are
readily volatile and therefore can be removed easily.
[0028] The conversion to the acid chlorides of formula (IV) is
preferably carried out in the presence of a diluent. Suitable for
this purpose are inert organic solvents or mixtures thereof. By way
of example, mention may be made of aliphatic, alicyclic, and
aromatic hydrocarbons, such as petroleum ether, hexane, heptane,
cyclohexane, methylcyclohexane, benzene, toluene, xylenes and
Decalin, halogenated hydrocarbons, such as chlorobenzene,
dichlorobenzenes, methylene chloride, chloroform,
tetrachloromethane, dichloroethane, trichloroethane and
tetrachloroethylene, ethers, such as diethyl ether,
tetrahydrofuran, 1,2-dimethoxyethane, 1,2-diethoxyethane,
diethylene glycol dimethyl ether and anisole, esters, such as
methyl acetate, ethyl acetate and butyl acetate, and sulfones, such
as sulfolane. Per mole of benzoic acid of the formula (V), 50 to
150 ml of diluent, for example, can be used.
[0029] It is advantageous to use an excess of the chlorinating
reagent, for example, 1.1 to 10 mol (preferably 1.2 to 3 mol) of
chlorinating reagent per mole of the benzoic acid of the formula
(V).
[0030] The reaction temperature for this stage can be varied within
a relatively wide range. For example, it can be between 0 and
150.degree. C., preferably between 20 and 120.degree. C.
[0031] The work-up following the reaction can, for example, be
carried out by distillation. If the preferred chlorinating reagents
are used, it is possible to readily distill off their excess and
the diluent which may be present, and to use the distillation
residue as crude product in the next stage.
[0032] The second stage of the process according to the invention,
the side-chain chlorination of the 3,5-dimethylbenzoyl chlorides of
the formula (IV), is novel. This side-chain chlorination is carried
out as a free-radical reaction. This can be achieved as a result of
elevated temperature, irradiation by a light source, and/or
addition of a free-radical initiator. Examples of suitable light
sources are incandescent lamps, preferably halogen lamps and
medium- and high-pressure mercury vapour lamps. Suitable
free-radical initiators are, for example, benzoyl peroxide,
di-tert-butyl peroxide, 2,2-aza-bis(isobutyronitrile), and
2-phenylazo-2,4-dimethyl-4-methoxy-val- eronitrile. Preference is
given to using a light source at elevated temperature. The reaction
temperature can, for example, be between 80 and 250.degree. C.,
preferably 100 to 220.degree. C., particularly preferably between
110 and 190.degree. C. Here, it is advantageous to start the
chlorination at relatively low temperatures, for example, 80 to
140.degree. C., and to continue to the end at relatively high
temperatures, for example, 160 to 250.degree. C.
[0033] The chlorinating agent used in this stage is generally
elemental chlorine.
[0034] Per mole of dimethylbenzoyl chloride of the formula (IV), it
is possible, for example, to use 6.3 to 18 mol (preferably 7.2 to
12 mol) of chlorine gas.
[0035] For work-up after the reaction it is possible to displace
any excess chlorine, e.g., by introducing an inert gas, such as
nitrogen, or by applying a vacuum. Crude product obtainable in this
way can be used directly in the next reaction stage, although, if
desired, it can also be purified, e.g., by vacuum distillation.
[0036] The third stage of the process according to the invention is
the fluorination of the 3,5-bis(trichloromethyl)benzoyl chlorides
of the formula (III) to give the 3,5-bis(trifluoromethyl)benzoyl
fluorides of the formula (II). One possibility for the preparation
of the 3,5-bis(trifluoromethyl)benzoyl fluoride is already known
from German Patent Specification 707,955 and can be transferred
analogously to the compounds in which X is fluorine or
chlorine.
[0037] The fluorination is carried out with anhydrous hydrofluoric
acid and/or antimony pentafluoride. In some instances, catalysts
may be added, e.g., Lewis acids, such as titanium tetrachloride,
boron trichloride, or antimony pentafluoride, which generally
increases the rate of the reaction. Preference is given to using
anhydrous hydrogen fluoride in a mixture with titanium
tetrachloride. It is also possible to add the Lewis acids after the
reaction has started.
[0038] Per mole of benzoyl chloride of the formula (III), it is
possible to use, for example, 7.7 to 21 mol (corresponding to a 10
to 200% excess) of anhydrous hydrogen fluoride or the corresponding
amount of antimony pentafluoride and, for example, 0 to 0.2 mol of
Lewis acids.
[0039] The fluorination can be carried out, for example, by
starting at a temperature below the boiling point (at atmospheric
pressure) of hydrogen fluoride, for example, at -20 to +15.degree.
C., and, to complete the reaction, continuing to the end at
relatively high temperatures, for example, at 100 to 180.degree. C.
As the result of the vapor pressure of the hydrogen fluoride,
pressures up to 100 bar can arise here, which necessitates the use
of reaction vessels which are appropriately pressure-resistant. The
hydrogen chloride liberated is decompressed, for example, at
temperatures above +20.degree. C. via a pressure relief valve.
[0040] The reaction mixture that is present following the
fluorination can be worked up by fractional distillation, for
example.
[0041] The final fourth stage of the process according to the
invention is the chlorine/fluorine exchange at the carbonyl group,
which has hitherto not been disclosed for these compounds. This is
carried out using silicon tetrachloride as reagent in the presence
of a further Lewis acid, for example, aluminum chloride, boron
trifluoride, titanium tetrachloride, iron trichloride, or mixtures
thereof.
[0042] Per mole of benzoyl fluoride of the formula (II), it is
possible, for example, to use 0.25 to 1 mol (1 to 4 equivalents),
preferably 0.3 to 0.5 mol, of silicon tetrachloride, and 0.01 to
0.1 mol, preferably 0.02 to 0.05 mol, of further Lewis acid.
[0043] This chlorine/fluorine exchange can, for example, be carried
out at temperatures between 0 and 70.degree. C., preferably between
20 and 50.degree. C. The procedure here may involve initially
introducing the further Lewis acid either with the benzoyl fluoride
of the formula (II) or with the silicon tetrachloride and metering
in the other component in each case. In this way, the evolution of
gas can be controlled easily.
[0044] The reaction mixture which is present following the
chlorine/fluorine exchange can be worked up, for example, by
firstly separating off the solid constituents, e.g., by filtration,
preferably following the addition of a filtration auxiliary, such
as cellulose or a zeolite. By fractional vacuum distillation of the
filtrate it is possible to obtain the prepared BTB in pure form. To
deactivate residues of the silicon tetrachloride and/or the further
Lewis acid, it may be advantageous to add a small amount of an
aryl- or alkylphosphine, for example, 0.1 to 1% by weight, to the
mixture to be distilled. Triphenylphosphine, for example, is
suitable for this purpose.
[0045] Using the process according to the invention, BTBs of the
formula (I) can be prepared in good yields from the readily
accessible 3,5-dimethylbenzoic acids of the formula (V) in a
process which can be readily and easily carried out on an
industrial scale. Viewed over all reaction stages, the yield is
significantly greater than 60% of theory.
[0046] Some of the compounds of the formulas (I) to (IV) are novel.
The present invention therefore also relates to
3,5-bis(trifluoromethyl)benzo- yl chlorides of the formula (Ia)
6
[0047] in which
[0048] X' is fluorine or chlorine,
[0049] 3,5-bis(trifluoromethyl)benzoyl fluorides of the formula
(IIa) 7
[0050] in which
[0051] X' is fluorine or chlorine,
[0052] 3,5-bis(trichloromethyl)benzoyl chlorides of the formula
(IIIa) 8
[0053] in which
[0054] X' is fluorine or chlorine, and
[0055] 3,5-dimethylbenzoyl chlorides of the fonnula (IVa) 9
[0056] in which
[0057] X' is fluorine or chlorine.
[0058] The preparation of compounds of the formulas (Ia) to (IVa)
is described above. They are novel intermediates for the
advantageous preparation of 3,5-bis(trifluoromethyl)benzoyl
chloride by the process according to the invention.
EXAMPLES
Example 1
3,5-Dimethylbenzoyl chloride
[0059] A 4 liter flat-flange reaction vessel was initially charged
with 1000 g of 3,5-dimethylbenzoic acid in 450 ml of toluene, and,
with stirring at 60.degree. C., 80 ml of thionyl chloride were
added dropwise over the course of 2 hours, a gas being evolved. The
mixture was then heated to boiling (internal temperature
102.degree. C.) and refluxed for 2 hours. Then, over the course of
1.5 hours, excess thionyl chloride and some of the toluene were
distilled off up to a head temperature of 102.degree. C. at
atmospheric pressure. The mixture was left to cool to 80.degree.
C., and the toluene was distilled off, now at 20 mbar. Residual
amounts were removed by distillation over a column at 20 mbar up to
the boiling point of 110.degree. C. (in the still). The residue
obtained was 1092 g (96.7% of theory) of 3,5-dimethylbenzoyl
chloride.
Example 2
3,5-Bis(trichloromethyl)benzoyl chloride
[0060] A reaction vessel equipped with an air-cooled UV immersion
lamp was initially charged, at 120.degree. C., with 1092 g of
3,5-dimethylbenzoyl chloride, and a total of 4340 g of chlorine
were introduced over 61 hours with UV irradiation and a steady
temperature increase to 180.degree. C. According to GC analysis,
100% of the starting material had then reacted. After the excess of
chlorine had been blown out with nitrogen, 2390 g (98.1% of theory)
of 3,5-bis(trichloromethyl)benzoyl chloride were left behind.
Example 3
3,5-Bis(trifluoromethyl)benzoyl fluoride
[0061] A 5 liter stainless steel stirred autoclave with inclined
condenser (operated with a coolant at a temperature of -10.degree.
C.) and pressure regulator was initially charged with 990 ml of
anhydrous hydrofluoric acid. Then, 1126 g of
3,5-bis(trichloromethyl)benzoyl chloride were added dropwise over
30 minutes at -5 to 0.degree. C., the evolution of hydrogen
chloride gas being only weak. The temperature was allowed to
increase to +20.degree. C. When the slight evolution of gas had
stopped (after 1.5 hours), 68 g of titanium tetrachloride were
added over 40 minutes. After the renewed evolution of gas had
subsided (after 2 hours), the apparatus was sealed, nitrogen was
injected to 10 bar, and the apparatus was heated in stages to
140.degree. C., the hydrogen chloride produced being continuously
decompressed at 25 bar. After 11 hours at 140.degree. C. the
reaction was complete. The autoclave was cooled and decompressed,
and the excess hydrogen fluoride was distilled off at atmospheric
pressure (248 g), and the residue was distilled under reduced
pressure (70 to 12 mbar) over a bridge (maximum head temperature:
84.degree. C. at 12 mbar). 43 g of a resinous residue remained. The
crude distillate was fractionally distilled under reduced pressure
over a 60 cm column packed with Wilson spirals (50 mbar,
140.degree. C. bath temperature, 75.degree. C. head temperature).
In addition to 105 g of distillation residue (not fully fluorinated
products which can be used again), 633 g (81% of theory) of
3,5-bis(trifluoromethyl)benzoyl fluoride with a purity of 99.9%
(GC, area %) were obtained.
Example 4
3,5-Bis(trifluoromethyl)benzoyl chloride
[0062] 1040 g of 3,5-bis(trifluoromethyl)benzoyl fluoride and 24 g
of aluminum chloride were initially introduced and heated to
40.degree. C. With stirring, 224 g of silicon tetrachloride were
added dropwise over 3 hours, where the temperature was controlled
and did not exceed 45.degree. C. The mixture was then stirred until
the evolution of gas had stopped (2 hours). 30 g of zeolite X133
were then added, and the mixture was filtered. This gave 1000 g of
a cloudy filtrate, which was admixed with 5 g of triphenylphosphine
and distilled at 12 mbar over a 70 cm column. This gave 623 g
(83.6% of theory) of 3,5-bis(trifluoromethyl)benzoyl chloride which
passed over at 68.degree. C. (bath temperature: 80.degree. C.).
Example 5
[0063] A stirred apparatus with gas feed and discharge to an
eliminator was initially charged with 100 g (0.593 mol) of
3,5-dimethylbenzoyl chloride together with 0.5 g of iron (III)
chloride, and 42 g of chlorine were introduced at 22-28.degree. C.
over the course of 3 hours. Fractional distillation gave 78 g of
2-chloro-3,5-dimethylbenzoyl chloride. Boiling range:
113-114.degree. C. at 5 mbar.
Example 6
[0064] A chlorination apparatus fitted with a UV irradiation lamp
was initially charged with 78 g of 2-chloro-3,5-dimethylbenzoyl
chloride in 100 ml of dry 4-chlorobenzotrifluoride, and 1 g of
phosphorus trichloride and 0.5 g of potassium chloride were added.
The temperature was initially set at 100.degree. C., and chlorine
was slowly introduced. Over the course of the chlorination, the
internal temperature was increased to solvent reflux. After 20
hours, 200 g of chlorine had been introduced, and the reaction
mixture was fractionally distilled. 119 g of
2-chloro-3,5-bistrichloromethylbenzoyl chloride passed over in the
boiling range 145-147.degree. C. at 0.2 mbar.
[0065] n.sub.D.sup.20:1.6025
Example 7
[0066] An autoclave made of stainless steel was charged with 100 ml
of HF and 2 ml of antimony pentachloride. At 0.degree. C., a
solution of 119 g of 2-chloro-3,5-bistrifluoromethylbenzoyl
chloride in 50 ml of dry dichloromethane was metered in. Nitrogen
was then injected to 10 bar, and then the temperature was increased
in stages to 145.degree. C. The hydrogen chloride which formed was
decompressed via a reflux condenser cooled to -15.degree. C. at 25
bar. After 9 hours, the evolution of hydrogen chloride had stopped,
and the system was cooled to room temperature. Hydrogen fluoride
that was still present and dichloromethane were distilled off. The
reaction product was subjected to fine distillation. 68 g of
2-chloro-3,5-bistrifluoromethylbenzoyl fluoride passed over in the
boiling range 76-77.degree. C. at 13 mbar.
[0067] n.sub.D.sup.20:1.4292
[0068] Although the invention has been described in detail in the
foregoing for the purpose of illustration, it is to be understood
that such detail is solely for that purpose and that variations can
be made therein by those skilled in the art without departing from
the spirit and scope of the invention except as it may be limited
by the claims.
* * * * *