CS270739B1 - Method of cis-3-/2,2-dichlorovinyl/-2,2-dimethylcyclopropancarboxylic acid's cyano-3-phenoxybenzyl ester preparation - Google Patents

Abstract

The method of preparation consists in being to cis-3- (2-2-dichlorvinyl) -2,2- sodium salt -dimethylcyclopropanecarboxylic acid of formula II, optionally optically active, v an inert hydrocarbon solvent and halogen-substituted derivatives thereof or oxygen, optionally in a water-inert mixture organic water-soluble solvent is miscible, optionally in the presence of a catalyst phase transfer based on quaternary ammonium salts, acts by the derivative <-cyano-3- -phenoxybenzyl alcohol of formula III, wherein X is halogen or p-toluenesulfonyloxy. The substance obtained is high insecticidal efficacy.

Description

The invention relates to a process for the preparation of cis-3- (2,2-dichlorovinyl) -2,2-dimethylcyclopropanecarboxylic acid (cis-permethrinic acid) -cyano-3-phenoxybenzyl ester of the formula I. This ester is known to have a high insecticidal activity (see e.g., M. Elliott, AW Farnham, NJ Jones, 0. M. Doderlund: Pest. Sci. £, 112, 1978; P. Ackermann, F. Bourgeouis, J. Drábek: Pestic. Sci. 11, 169, 1980) .

Said ester of formula I can be obtained by reacting cis-permethrinic acid chloride with α, ω-cyano-3-phenoxybenzyl alcohol, optionally prepared in situ (see, e.g., British Pat. No. 1,567,531, British Pat. No. 1,540,632). DE No. 2,951,496, EP No. 0 025 925). However, the disadvantage of this process is the low stability of both reagents, which is reflected in not entirely satisfactory yields, but in particular in unsatisfactory purity of the product (see EP No. 0 067 461). These shortcomings are partly addressed by alternative processes involving the reaction of free cis-permethrinic acid with β-cyano-3-phenoxybenzyl halide or with the corresponding arylsulfonate (see, e.g., Brit, U.S. Pat. No. 1,559,799, EP No. 067 461).

The process for the preparation of the ester of the formula I according to the invention eliminates these disadvantages by applying to the sodium salt of cis-permethrinic acid of the formula II, optionally optically active, in an inert solvent from the group of hydrocarbons and their halogen- or oxygen-substituted derivatives The water-inert organic solvent mixture, which is sparingly miscible with water, optionally in the presence of a phase transfer catalyst based on quaternary ammonium salts, is treated with a cyano-3-phenoxybenzyl alcohol derivative of the formula III in which X is halogen or p-toluenesulfonyloxy. The crystalline sodium salt of cis-permethrinic acid of the formula II is partially or completely dissolved in an inert organic solvent, but preferably in a two-phase mixture of water-inert and water-miscible solvents. If the solvent of the formula I according to the invention is prepared in a two-phase water-inert solvent with limited water miscibility, phase transfer catalysts known per se are used (e.g. described in the monograph EW Oehmlow, SS Oehmlow: Phase Transfer Catalysis, 2nd Ed. , Verlag Chemie 1983), preferably selected from the group of quaternary ammonium salts having a carbon number of 4 to 16. It is advantageous to work in a hydrocarbon solvent or in a chlorinated hydrocarbon solvent. The reaction can be carried out, depending on the other reaction variables, either at room temperature or at elevated temperature, with temperatures of 40 to 70 ° C being particularly advantageous. The preparation of the cis-ester of the formula I according to the invention can be carried out with either the racemic or optically active sodium salt of the formula II, the initial geometric and optical configuration of the cyclopropane ring remaining unchanged. When working with an optically active cis-permethrin acid salt, the optically active α-cyano-3-phenoxybenzyl cis-permethrinic acid ester of formula I is obtained. The advantage of the optically active ester of formula I with the IR configuration is the increased insecticidal activity. .

The advantage is the easy availability of the sodium salt of permethrin acid. The possibility of its direct use for the preparation of the ester of the formula I, without prior isolation of cis-permethrinic acid, or its conversion into the chloride, therefore represents an obvious economic and technical advantage in comparison with the prior art. Another comparative advantage of the new process is also the surprisingly high purity of the product, which can be further increased if necessary by possible recrystallization of the sodium salt of cis-permethrinic acid used. >

The process according to the invention is further elucidated by means of examples which do not limit its scope.

Example 1.

0.486 g (2.1 mmol) of sodium cis-permethrinate, 0.55 g (1.91 mmol) of benzyl bromide of formula III (X = Br), 0.03 g (0.09 mmol) of tetrabutylammonium bromide were weighed into a 25 ml flask. , 2 ml of toluene and 1 ml of water, and the mixture was stirred vigorously at 70 ° C for 6 hours. After cooling, the toluene layer was washed successively with 1 ml of 5% aqueous sodium carbonate solution and 1 ml of water. After evaporation and drying in vacuo (80-90 [deg.] C./1-2 mm Hg), 0.73 g (92% of theory) of the cis-ester of the formula I are obtained with a purity of 3-98% (GLC).

CS 270739 Bl

Example 2

The procedure of Example 1 was followed, but instead of the benzyl bromide of formula III (X = Br), 0.725 g (1.91 mmol) of the corresponding benzyl p-toluenesulfonate of formula III (X = OTs) was added to the reaction. 0.71 g (90% of theory) of a cis-ester of formula I containing less than 1% of the trans isomer was obtained.

Example 3

The procedure of Example 2 was followed, except that the corresponding salt of the optically active acid was used instead of the racemic sodium cis-permethrinate. 0.71 g (90% of theory) of the cis-ester of formula I, = 16.5 ° (10% benzene), was obtained.

Example 4

The procedure of Example 2 was followed, except that xylene was used as the solvent instead of toluene. Yield 0.75 g (95% of theory) of a cis-ester of formula I containing less than 1% of the trans-isomer (GLC).

Example 5

The procedure of Example 2 was followed, except that 0.02 g (0.09 mmol) of triethylbenzylammonium bromide was used as the phase transfer catalyst instead of tetrabutylammonium bromide. Yield 0.64 g (81% of theory) of a cis-ester of formula I containing less than 1% of the trans isomer (GLC).

Example 6

0.486 g (2.1 mmol) of sodium cis-permethrinate, 0.725 g (1.91 mmol) of benzyl p-toluenesulfonate III (X = OTs) were added to a 25 ml flask, 10 ml of acetone were added and heated to reflux with vigorous stirring. The acetone was removed on an evaporator under reduced pressure, 5 ml of water and 5 ml of ether were added to the residue, and 0.52 g (65% of theory) of the crude cis-ester of formula I was obtained from the ether layer after evaporation.

Example 7

The procedure was as in Example 2 in a 50 l glass pear, weighing 10,000 times larger. 7.5 kg (95% of theory) of a cis-ester of formula I containing less than 1% of the trans-isomer were obtained.

Example B

The procedure of Example 1 was followed, using chlorobenzene instead of toluene. The cis-ester of formula I was obtained in 90% yield.

Example 9

The procedure of Example 1 was followed, except that heptane was used instead of toluene. The cis-ester of formula I was obtained in 70% yield.

Claims (4)

OBJECT OF THE INVENTION A process for the preparation of cis-3- (2,2-dichlorovinyl) -2,2-dimethylcyclopropanecarboxylic acid .beta.-cyano-3-phenoxybenzyl ester of the formula I, characterized in that the sodium salt of cis-3- (2,2-dichlorovinyl) -2,2-dimethylcyclopropanecarboxylic acid is characterized in that -dichlorovinyl / -2,2-dimethylcyclopropanecarboxylic acids of the formula II, optionally optically active, in an inert organic solvent from the group of hydrocarbons and their halogen- or oxygen-substituted derivatives, optionally in a water-inert organic solvent mixture with limited miscibility, optionally in the presence of a phase catalyst. on the basis of quaternary ammonium salts, acts with a <2-cyano-3-phenoxybenzyl alcohol derivative of the general formula III, in which X represents a halogen atom or a p-toluenesulfonyloxy group. 2. The process according to item 1, characterized in that the reaction takes place in a two-phase mixture of water and an aromatic hydrocarbon. CS 270739 Bl 3 3. The process according to items 1 to 2, characterized in that the reaction takes place in an environment of water and an aromatic hydrocarbon having a number of carbon atoms of 7 to 9. 4. The process according to items 1 to 3, characterized in that the reaction is carried out in the presence of a phase transfer catalyst based on a quaternary ammonium salt having a carbon number of 4 to 16.