CS209821B2 - Method of making the new phenyl vinegar acids event.the reactive derivatives thereof - Google Patents

Description

The invention relates to a process for the preparation of novel phenylacetic acids or their reactive derivatives, which are the starting materials for the preparation of insecticidally and acaricidally active novel fluorine-containing phenylacetic acid esters of the general formula I

(AND)

X <

in which

R is an optionally fluorine substituted phenoxybenzyl group or an aryloxyphenoxybenzyl group,

R ¹ is isopropyl or cyclopropyl,

X is hydrogen,

^X 'is where R is 4-fluoro-3-fenoxybenzylovou group which is optionally substituted in position and the cyano, fluoroalkoxy having 1 to 4 carbon atoms or fluoralkylthioskupinu having 1-4 carbon atoms or together with symbo1 hem X are fluorine substituted methylenedioxy or ethylenedioxy, and furthermore in the event that R ¹ represents cyclopropyl and R is an optionally alpha-cyano substituted 4-fluoro-3-fenoxybenzylovou group, represents hydrogen, halogen or together with X an optionally fluorine-substituted methylenedioxy or optionally fluoro substituted ethylenedioxy and in cases where R is other than an optionally substituted 4-fluoro-3-phenoxybenzyl substituted by a-cyano group, it is hydrogen, OCHF2, SCF3, and optionally together with X is -OCF2O- or -OCHFCF2O-.

The novel phenylacetic acids or their reactive derivatives corresponding to the general formula (XII)

(XII) in which

X ² is at position 3 and / or 4-position residue - OCH 2 - SCHF2 - SCCIF2, -SCF3 and at the 3 and 4 residues or -OCH2CF2O-- -OCHFCF2O-,

R @ ¹ represents a C2 -C4 alkyl group, a C2 -C4 alkenyl group or a cyclopropyl group and

Z ¹ is halogen, preferably chlorine or fluorine, hydroxy or -O-alkyl, wherein the alkyl contains 1 to 4 carbon atoms, are obtained according to the invention by reacting compounds of formula IV

in which:

X ² is as defined above, reacted with a compound of formula VII

R ¹ -Hal (VII) where

R ¹ has the abovementioned meaning and

Hal represents chlorine, bromine or iodine in the presence of a base and optionally in the presence of a solvent and / or in the presence of a phase transfer catalyst.

Compounds of formula VI

X ² and R ¹ are as defined above, with an alcohol of formula V

Alkyl-OH (V)

CH "CN (VI) wherein" alkyl "contains 1 to 4 carbon atoms, in the presence of an acid catalyst, and the resulting imino ester is hydrolyzed to an ester, which is optionally saponified to an acid and optionally reacted with a halogenating agent, or If X ² is in the 3-position or 4-position of the radicals "OCH 2 CF 2 O" or "OCHFCF 2 O", the CN group of the compound of formula IV is saponified to a COOH group and optionally reacted with a halogenating agent.

Compounds of formula IV wherein

X ² is as defined above, is new and can be prepared by treating compounds of formula (VIII)

CH ₂ H _Ál (Vlil)

in which

X is as defined above and

Hal is chlorine or bromine, reacted with hydrogen cyanide or preferably; with an alkali metal cyanide, optionally in the presence of a catalyst.

Examples of compounds of formula XII are:

3-difluoromethoxy-o-ethylphenylacetic acid (and the corresponding chloride, methyl and ethyl esters) in which:

X ² and R ¹ are as defined above, are new and can be prepared by treating compounds of formula VI

98 2 1

4-difluoromethoxy-α-ethylphenylacetic acid (and the corresponding chloride, methyl and ethyl esters),

3-difluoromethoxy-α-isopropylphenylacetic acid (and the corresponding chloride, methyl and ethyl esters),

4-difluoromethoxy-α-isopropylphenylacetic acid (and the corresponding chloride, methyl and ethyl esters),

3-Difluoromethylthio-α-isopropylphenylacetic acid (and the corresponding chloride, methyl and ethyl esters),

4-difluoromethylthio-α-isopropylphenylacetic acid (and the corresponding chloride, methyl and ethyl esters),

4-difluoromethylthio-or-ethylphenylacetic acid (and the corresponding chloride, methyl and ethyl esters),

4-difluorochloromethylthio-n-ethylphenylacetic acid (and its chloride, methyl ester and ethyl ester),

4-difluorochloromethylthio-α-isopropylphenylacetic acid (and its chloride, methyl ester and ethyl ester),

3-trifluoromethylthio-α-ethylphenylacetic acid (and its chloride, methyl ester and ethyl ester),

3-Trifluoromethylthio-n-isopropylphenylacetic acid (and its chloride, methyl ester and ethyl ester),

4-Trifluoromethylthio-α-isopropylphenylacetic acid (and its chloride, methyl ester and ethyl ester),

4-trifluoromethylthio-α-ethylphenylacetic acid (and its chloride, methyl ester and ethyl ester),

3.4-difluoroethylenedioxy-α-isopropylphenylacetic acid (and its chloride, methyl and ethyl esters),

3,4-trifluoromethylenedioxy-α-ethylphenylacetic acid (and its chloride, methyl and ethyl esters),

3,4-trifluoroethylenedioxy-α-isopropylphenylacetic acid (and its chloride, methyl ester and ethyl ester); and

3,4-difluoroethylenedioxy-n-ethylphenylacetic acid (and its chloride, methyl ester and ethyl ester).

The novel acids, halides or esters of the acid of formula XII can be prepared according to the procedure described above from the compounds of formula IV.

In the case where X ² in position 3 and / or 4-position represents a residue - OCHF, -SCHFz, -SCCIF2, -SGF3, would not remain with X ² under drastic conditions as are necessary for the saponification (hydrolysis) of the nitrile to the carboxylic acid , remain unchanged, and therefore the compound of formula IV can in these cases be converted directly via hydrolysis to the compound of formula XII Z ¹ --- OH.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for such cases which would allow the conversion of nitriles, under as mild conditions as possible, under which these X ² residues remain unchanged.

It has now been found that a nitrile group can be converted to an ester group without disturbing the X ² moieties by dissolving the nitriles of formula IV in an alcohol of formula V [alkyl-OH wherein the alkyl contains 1 to 4 carbon atoms] and the solution is saturated with hydrogen chloride at about -10 ° to -50 ° C, preferably at 0 to 20 ° C. After a period of standing, the imino ester forms from which the ester is formed by the action of water. This ester can also be processed immediately in the form of an aqueous solution.

This ester can also be converted directly to a compound of formula I by re-esterification or saponified in the usual manner to an acid and then optionally treated with conventional halogenating agents such as SOCl 2, COCl 2, phosphorus trichloride, phosphorus pentachloride, oxalyl chloride or oxalyl bromide formation of acid halides.

The nitrile group of compounds of formula IV wherein X ² at the 3 and 4 positions is -O-CH 2 CF 2 O- or -OCHFCF 2 O- can be saponified under acidic or alkaline conditions.

Suitable saponification agents are all customary saponification agents, such as sulfuric acid, acetic acid, or preferably alkali metal hydroxides. The saponification is carried out at an elevated temperature, for example at a temperature of from 50 to 160 ° C, preferably at 80 to 135 ° C

However, it is also possible, as described above, to convert a nitrile group to an ester group by dissolving the nitriles in an alcohol of formula V with alkyl-OH (V) wherein the alkyl contains 1 to 4 carbon atoms and saturates this solution at about 0 to 20 ° C with hydrogen chloride. After a period of standing, the imino ester is formed from which an ester is formed by the action of water. It can also be processed immediately in the form of an aqueous solution.

The ester can then be converted directly to the compound of formula (I) by re-esterification or saponified to the acid in the usual manner and optionally reacted with conventional halogenating agents such as SOCl 2, COCl 2 PCl 3, PCl 5, oxalyl chloride or oxalyl bromide PBrj to form the acid halide.

Examples of novel compounds of formula IV are:

3.4-difluoroethylenedioxy-α-ethylphenylacetonitrile,

3,4-difluoroethylenedioxy-α-isopropylphenylacetonitrile,

3,4-trifluoroethylenedioxy-α-ethylphenylacetonitrile,

3,4-trifluoroethylenedioxy-α-isopropylphenylacetonitrile,

3-difluoromethoxy-α-ethylphenylacetonitrile,

3-difluoromethoxy-α-ethylphenylacetonitrile,

3-difluoromethoxy-n-isopropylphenylacetonitrile,

4-difluoromethoxy-α-isopropylphenylacetonitrile,

4-difluoromethylthio-α-isopropylphenylacetonitrile,

3-difluoromethylthio-of-isopropylphenylacetonltril,

3-Difluorochloromethylthio-α-isopropylphenylacetonitrile

4-Difluorochloromethylthio-α-isopropylphenylacetonitrile

3-Trifluoromethylthio-n-ethylphenylacetonitrile

4-Trifluoromethylthio-α-ethylphenylacetonitrile

3-Trifluoromethylthio-α-isopropylphenylacetonitrile a

4-Trifluoromethylthio-α-isopropylphenylacetonitrile.

The novel compounds of formula IV can be obtained as above from compounds of formula VI by alkylation with compounds of formula VII.

This reaction can be illustrated by the following reaction scheme:

+ RH & 1 ⁺ base

- H-Hat

The alkylation is carried out in the presence of an equimolar amount of the base (based on R 4 Hal, which is preferably used in excess). The solvent can be used with or without a solvent.

Suitable bases are, for example: sodium hydroxide, potassium hydroxide, alkoxides such as sodium methoxide, sodium ethoxide, sodium isopropoxide or sodium tert-butoxide and potassium carbonate.

Suitable solvents are, in particular, alcohols such as methanol, ethanol, isopropanol. Preferably, sodium hydroxide, potassium hydroxide or potassium carbonate is used in the presence of phase transfer catalysts. Suitable phase transfer catalysts are, in particular, quaternary ammonium salts, such as tetrabutylammonium chloride and tetrabutylammonium bromide, benzyltriethylammonium chloride or methyltrioctylammonium chloride. It can be operated in the presence of water, but also in an anhydrous environment.

Examples of the compound of formula VI include:

3-difluoromethoxyphenylacetonitrile,

4-difluoromethoxyphenylacetonitrile,

3-Difluoromethylthiophenylacetonitrile

4-Difluoromethylthiophenylacetonitrile

3-Trifluoromethylthiophenylaceto, nitrile,

4-Trifluoromethylthiophenylacetonitrile

3-difluorochloromethylthiophenylacetonitrile,

4-Difluorochloromethylthiophenylacetonitrile

3,4-difluoroethylenedioxyphenylacetonitrile;

3,4-trifluoroethylenedioxyphenylacetonitrile.

Examples of compounds of formula VII include: ethylene chloride, ethyl bromide, ethyl iodide, 2-chloropropane, 2-bromopropane, 2-iodopropane and 1-bromo-2-methylpropane.

The novel compounds of formula VI are obtained according to the above-described process from compounds of formula VIII by treatment with hydrogen cyanide or preferably an alkali metal cyanide.

The compounds of formula VIII are known or can be obtained by known methods. These compounds, when X ² is -OCF ² O -, are obtained by forming a compound of formula

with compounds of the formula

FX ¹ is reacted with anhydrous hydrofluoric acid, or when X is -OCH 2 CF 2 O-, or OCHFCF 2 O-, is obtained by reacting a compound of formula

HIM,

HIM'

OH,

FX ² in which

X ¹ is halogen and

X ² is hydrogen or halogen, and then halogenated to form the benzyl halide. The process for preparing compounds of formula VI can be illustrated by the following reaction scheme:

CH-Hal ² MeCN

-MECO oh ₂ cn

Me - Na, K.

Chlorides or bromides are used as halides. The cyanide used is preferably an alkali metal cyanide such as sodium cyanide or potassium cyanide.

This reaction is carried out according to principally known methods (Houben-Weyl, Vol. VIII, p. 294).

Advantageously, phase transfer catalysts such as quaternary ammonium salts or amines such as triethylamine, tripropylamine, tributylamine (Synthesis 1973, p. 448, Synthetic Comm. 6, 193 [1976]) may also optionally be solvent-free.

Acid derivatives of the formula XII, in which X ² is in the 3- and 4-position of the group -OCF 2 O- and Z ¹ is fluorine and R ¹ is a C 2 -C 4 alkyl group, are also obtained by reacting compounds of formula IX with anhydrous hydrofluoric acid according to the following reaction scheme:

(R ¹ - C 2 -C 4 alkyl).

This reaction can be carried out at temperatures from -20 ° C to 80 ° C, particularly preferably at 0 ° C to 40 ° C.

Hydrofluoric acid must be used in at least a stoichiometric amount, but its excess is generally favorable. Thus, the amount of hydrofluoric acid is preferably two to three times the stoichiometric amount, yet the excess may be even greater. The reaction can be carried out in the presence of solvents as well as without solvents. Suitable solvents are, in general, inert, aprotic liquids. Examples are methylene chloride, trichlorofluoromethane, carbon tetrachloride, chlorobenzene or nitrobenzene. The amount of solvent is of no importance to the process of the invention. Thus, the reaction is preferably carried out without solvent if the starting materials are liquid.

In general, the reaction is carried out at atmospheric pressure, but can also be carried out under positive pressure.

You can do the following:

The necessary amount of hydrofluoric acid is introduced into the reaction vessel at a temperature of about -10 ° C and compounds of formula IX are added with stirring. The temperature must be selected so that the evolution of hydrogen chloride begins immediately and the resulting gas is passed through a reflux condenser into the receiver, where it condenses and is neutralized. The temperature can be raised somewhat after the addition is complete. The reaction mixture was stirred until gas evolution had ceased, and then excess hydrofluoric acid was distilled off at atmospheric pressure or under reduced pressure. The residue is a reaction product which can be purified, for example, by distillation.

The novel compounds of formula IX are obtained by reacting compounds of formula X with or without diluents. Suitable diluents are, for example: phosphorus trichloride, POCl3, chlorine-containing solvents such as carbon tetrachloride, chlorobenzene or dichlorobenzene. The use of chlorine is preferably carried out under conditions in which radials are formed, for example under illumination.

The temperature range is between 50 and 150 degrees Celsius, preferably between 75 and 130 ° C.

The compounds of formula IX can be used in the above-described process without further purification.

The following examples illustrate the invention:

O·

.CH-COCl (λ)

Example 1

HF ₂

C-O-CH-CO-Cl-y in which

CH (CH 3

R ¹ represents a C 2 -C 4 alkyl group with a chlorinating agent. Compounds of formula X are known (DOS 2,335,347).

This process can be illustrated by the following reaction scheme:

/ 0 ·

CH-CO->

L ¹

R ¹ Cl .0

CLC

CH-COCl

Suitable chlorinating agents are chlorine and phosphorus pentachloride. One g of 1-difluoromethoxy-or-isopropylphenylacetic acid can be dissolved in 100 ml of thionyl chloride and the solution is heated to boiling for 1 hour. After excess thionyl chloride was distilled off, the residue was distilled under high vacuum. 4-Difluoromethoxy-.alpha.-isopropylphenylacetic acid chloride is obtained, b.p. 93 DEG-99 DEG C./0.2 mbar.

In an analogous manner to that described in the above example, 3-difluoromethoxy-α-isopropylphenylacetic acid chloride as well as 4-trifluoromethylthio-α-isopropylphenylacetic acid chloride are obtained.

The following compounds were also prepared in an analogous manner:

boiling point

to 92 ° C / 40 Pa to 82 ° C / 33.3 Pa

Example 2

E ₂ CH-O-y-CH-COOH

Dissolve CH (CH 2 g of β-difluoromethylenedioxy-α-isopropylphenylacetic acid nitrile in 200 mL of absolute methanol and saturate this solution at 0-10 ° C. After standing overnight water is added and the mixture is stirred for some time. The methyl ester can be purified by distillation (boiling point: 80 ° C / 26.6 Pa) or can also be directly saponified by boiling under a reflux condenser for 4 hours and quadruple with 15% methanolic potassium hydroxide solution. The aqueous phase is acidified with concentrated hydrochloric acid and also extracted twice with methylene chloride, and the two extracts are combined, dried over sodium sulfate, filtered and evaporated on a rotary evaporator.

There was obtained 1'-difluoromethylenedioxy-α-isopropylphenylacetic acid, m.p. 63 ° C.

In an analogous manner to that described in this example, 3-difluoromethoxy-n-isopropylphenylacetic acid and 4-trifluoromethylthio-α-isopropylphenylacetic acid are obtained.

The following compounds are also prepared analogously:

formula

aj Production of compounds of formula IV

Example 3

Example 4 '0'

CH-CN

CHÍCHJz

98.5 g of 4-difluoromethoxyphenylacetonitrile, 133 g of 2-bromopropane and 20 g of tetrabutylammonium bromide are introduced and the reaction mixture is heated to boiling. 121 g of 50% potassium hydroxide are then added dropwise over 2 hours and the mixture is heated at reflux for a further 8 hours. After cooling, water is added, the mixture is neutralized, the organic phase is separated and distilled. 4-difluoromethoxy-2-isopropylphenylacetonitrile boils at 102-109 ° C / 40 Pa.

The 3-difluoromethoxy-.alpha.-isopropylphenylacetonitrile obtained in an analogous manner boils at 98 DEG-102 DEG C./2 mm Hg.

78.7 g of 3,4-difluoromethylenedioxyphenylacetonitrile, 60 g of bromopropane and 5 g of tetrabutylammonium bromide are introduced and the reaction mixture is heated to boiling. 54 g of 50% potassium hydroxide are then added dropwise over 2 hours, and the reaction mixture is then heated at reflux for a further 8 hours. After cooling, water is added, the mixture is neutralized, the organic phase is separated and distilled. 3,4-difluoromethylenedioxy-or-isopropylphenylacetonitrile boils at 97-100 ° C.

9! 8 2 1

Example 5

b) Preparation of compounds of formula VI

Example 9

O.

ch ₂ cn

The procedure was carried out in an analogous manner, but using 78 g of 2-iodoethane instead of 2-bromopropane.

Example 6

157 g of 3,4-difluoromethylenedioxybenzyl bromide, 5 g of tetrabutylammonium bromide and a 30% aqueous solution of sodium cyanide containing 34.3 g of sodium cyanide are heated at 100 DEG C. for 1 hour. After cooling, the mixture is extracted twice with methylene chloride, the organic phase is dried over sodium sulphate, filtered and distilled. 3,4-Difluoromethylenedioxyphenylacetonitrile boils at 104 to 108 ° C / 50 mm Hg.

Example 10

297.5 g of 3,4-trifluoromethylenedioxyphenylacetonitrile, 200 g of 2-bromopropane and 30 g of tetrabutylammonium bromide are heated to boiling. Then 180 g of 50% potassium hydroxide is added dropwise over 3 to 4 hours. The reaction mixture is then boiled for a further 6 hours. After cooling, water is added, the mixture is neutralized, the organic phase is separated and distilled. 3,4-trifluoroethylenediocy-1-isopropylphenylacetonitrile boils at 105-110 ° C / 13.3 Pa.

Example 7

The procedure is analogous to the above example, but 300 g of 2-iodoethane is used instead of 200 g of 2-bromopropane, b.p. 98-102 ° C / 20 Pa.

Example 8

CH (CH ₃ ) ₂ F ₃ C 5 H 2 -CH-CN

235 g of 4-trifluoromethylthiophenylacetonitrile, 160 g of 2-bromopropane and 20 g of tetrabutylammonium bromide are introduced and the reaction mixture is heated to boiling. 145.5 g of 50% potassium hydroxide are then added dropwise over 3 hours, and the reaction mixture is then heated at reflux for 3 hours. The treatment is carried out as in the above example. 4-Trifluoromethylthio-.alpha.-isopropylphenylacetonitrile boils at 97-103 DEG C./40 mbar.

CH 2 CN

135 g of potassium cyanide are dissolved in 225 ml of water and 20 g of tributylamine and 350 g of 3,4-trifluoroethylenedioxybenzyl chloride are gradually added. The reaction mixture is heated at 100 ° C for 1 hour with stirring, then cooled, extracted twice with methylene chloride, the organic phase is dried over sodium sulphate, filtered and distilled. 3,4-trifluoroethylenedioxyphenylacetoniltril boils at 109-110 ° C / 1.3 Pa.

Example 11

F ₂ C CH _Z CN

4-difluoromethoxybenzylcyanide

A) 270 g of 4-difluoromethoxytoluene in 800 ml of carbon tetrachloride are introduced and 300 g of N-bromosuccinimide are added. After addition of azoisobutyronitrile at the spatula tip, the reaction mixture was heated to reflux. After 8 hours, the reaction mixture was cooled, the insoluble succinimide was filtered off and the filter residue was washed with carbon tetrachloride. The carbon tetrachloride was distilled off from the reaction solution and the crude product was purified by fractional distillation. 250 g of 4-difluoromethoxybenzyl bromide are obtained. Boiling point 82 DEG-85 DEG C./0.5 mm Hg. n _D ²⁰ = 1.5200.

Dissolve 100 g of potassium cyanide in 160 ml of water and then add 15 g of tetrabutylammonium bromide and 230 g of 4-difluoromethoxybenzyl bromide. The reaction mixture was then heated at 100 ° C for 1 hour and, after cooling, extracted twice with methylene chloride. After drying over sodium sulfate, the organic phase is first freed from the solvent and then distilled. 145 g of 4-difluoromethoxybenzyl cyanide are obtained.

Boiling point: 106-108 ° C / 40 Pa, n _D ²⁰ = 1.4822.

The 3-difluoromethoxy derivatives are obtained analogously to the previous example.

Example 12 f ₃ CS- <Q> -CH ₂ CN

4-Trifluoromethylmercaptobenzyl cyanide

A] 700 g of 4-trifluoromethylmercaptotoluene in 2000 ml of carbon tetrachloride are introduced into a glass-cooling apparatus and the mixture is heated to reflux. The reaction solution is irradiated with an ultraviolet lamp. 3 ml of bromine are added before chlorination. When the color of the bromine disappears, 200 g of chlorine are introduced for 6 hours. Fractionated distillation through a 40 cm high packed column gives 560 g of 4-trifluoromethylmercaptobenzyl chloride in addition to the non-chlorinated starting material. Boiling point 97-98 ° C / 1866.5 Pa. n _D ²⁰ = 1.5072.

B) 75 g of sodium cyanide are dissolved in 200 ml of water and 15 g of tetraethylammonium chloride and 450 g of 4-trifluoromethylmercaptobenzyl chloride are added. The reaction mixture was stirred at 110 ° C for 1 hour and then cooled. The cold reaction mixture was diluted with 200 mL of water and then extracted twice with methylene chloride. After drying, it is extracted twice with methylene chloride. After drying the organic phase, the solvent was distilled off and the crude product was purified by distillation. 410 g of 4-trifluoromethylmercaptobenzyl cyanide are obtained. Boiling point 95-97 ° C / 20 Pa.

n _D 20 = 1.5025.

C) preparing compounds of formula VIII

Example 13

mane for 5 hours to boil. After cooling, the reaction mixture was filtered, the filter residue was washed with a small amount of carbon tetrachloride and the filtrate was distilled. 3,4-Difluoromethylenedioxybenzyl bromide is obtained with a boiling point of 108 to 111 ° C / 2000 Pa.

Example 14

In a glass chlorination apparatus, 1000 g of 3,4-trifluoroethylenedioxytoluene are introduced at 120 DEG C. and irradiated with an ultraviolet lamp. 300 g of chlorine are then introduced for 7 hours. After the introduction of chlorine is complete, the reaction mixture is allowed to react for a further 20 minutes and then a short stream of nitrogen is introduced into the mixture.

Distillation through a packed column yields: 195 g of starting material, bp 76 ° C / 2000 Pa, 58 g of intermediate fraction, bp 77-115 ° C / 2000 Pa, 645 g of 3,4-trifluoroethylenedioxybenzyl chloride, bp 115 ° C / / 2000 Pa (n _D ²⁰ = 1.4906).

d) Preparation of the starting compounds or the preparation of the compounds of formula VIII

Example 1 5

200 ml of anhydrous hydrogen fluoride are introduced into the reaction vessel at 0 DEG C. and then 190 g of 3,4-dichloromethylenedioxytoluene (cf. J. Chem. Soc _; 93, 563) are added dropwise. After completion of the evolution of hydrogen chloride, the reaction mixture was warmed to 20 ° C, stirred for 1 hour, and then excess hydrogen fluoride was distilled off under reduced pressure. 3,4-difluoromethylenedioxytoluene boils at 74-78 ° C / 6933 Pa.

Example 16

172 g of 3,4-difluoromethylenedioxytoluene, 180 g of N-bromosuccinimide and azoisobutyroniton spatula tip are mixed with 1000 ml of carbon tetrachloride and the reaction mixture is introduced together with 110 g of potassium hydroxide in 124 g of 4-methylpyrocatechin.

300 ml of tetramethylene sulfone at 110 degrees Celsius. 170 g of trifluoromethylene are then introduced over 4 hours. The reaction mixture is then distilled at 2000 Pa through a column, collecting fractions up to a transition temperature of 85 ° C. After separation of the aqueous phase in the receiver, the product is distilled again. When the boiling point of 70-72 ° C / 1600 mbar, a 3,4-trifluorethylendioxytoluen (n _D ²⁰ - 1.4565).

Claims (2)

Subject A process for the preparation of novel phenylacetic acids or their reactive derivatives of the general formula (XII) R ¹ (XTL) wherein X ² is at position 3 and / or 4-position residues -OCHF2, -SCHFz - SCCIF2, -SCF3 and at the 3 and 4 residues or -OCH2CF2O- -OCHFCF2O-, R @ ¹ represents a C2 -C4 alkyl group, a C2 -C4 alkenyl group or a cyclopropyl group and Z ¹ represents halogen, preferably chlorine or fluorine, hydroxy or -O-alkyl, wherein the alkyl contains 1 to 4 carbon atoms, characterized in that the compounds of formula IV are reacted YNÁtEZU in which X ² and R ¹ are as defined above, with an alcohol of formula V Alkyl-OH (V), wherein the "alkyl" contains 1 to 4 carbon atoms, in the presence of an acid catalyst, and the resulting imino ester is hydrolyzed to an ester, which is optionally saponified to an acid and optionally reacted with a halogenating agent, or If X ² is in the 3-position or 4-position of the radicals "OCH 2 CF 2 O" or "OCHFCF 2 O", the cyano group of the compound of formula (IV) is saponified to a -COOH group and optionally reacted with a halogenating agent. 2. Method of claim 1 for the preparation of phenylacetic acid of formula XII wherein X2 is -SCF3 residue at position 4, R ¹ is isopropyl and Z ¹ is hydroxy, characterized in that as in the compound of formula 0becného IV wherein X ² and R ¹ are as defined above in this point.