CS269408B1 - Crystalline cia-permethrin sting salt and its preparation process - Google Patents

Abstract

Crystalline sodium salt of ois-permethrinic acid of formula I is an important intermediate in the production of insecticidal substances. The method of its preparation consists in treating the sodium salt of 2,2-dimethyl-3-/2.2,2-trichloroethyl/cyclopropanecarboxylic acid of formula II in the ois or cis and trans configuration with sodium hydroxide in water, optionally in the presence of an inert organic solvent and optionally in the presence of sodium halide at a temperature of 70 to 100 °C, after which the reaction mixture is cooled to a temperature of -20 to +20 °C and the acid formed on standing is separated. The crystalline sodium salt of cis-permethrin acid can also be prepared by treating the 4,6,6,6-tetrachloro-3,3-dimethylhexanoic acid ester of the general formula III, where R is methyl or ethyl, with sodium hydroxide in an inert organic solvent first in the absence and then in the presence of water at a temperature of -10 to 100 °C, after which the reaction mixture is optionally cooled to a temperature of -20 to +20 °C and the crystalline precipitate of the cis-permethrin acid salt formed by standing is separated. Crystalline sodium salt of cis-permethrin acid can also be prepared by the action of Bodny's hydroxide on cis- or cis- and trans-permethrin acid of formula IV in water or in a mixture of water - inert organic solvent at a temperature of 20 to 90 °C, after which the mixture is cooled to a temperature of -20 to +20 °C and the precipitated crystalline precipitate of the cis-permethrin acid salt is separated and optionally recrystallized.

Description

The present invention relates to a crystalline sodium salt of cis-permethrin acid of formula I.

It is known that some esters of permethrin acid are effective insecticides, with cis-permethrin acid esters being generally more effective than the corresponding trans-permethrin acid esters. The preparation of cis-permethrin acid and its derivatives is therefore of interest from a technical point of view. The method for preparing the cis-trans isomeric esters of permethrin acid (P. Martin, Helv. Chim. Anta 66, 1189, 1983) of formula I is carried out by dehydrohalogenating the acid salt of formula II by heating with aqueous sodium hydroxide, followed by adoxidation to obtain free permethrin acid containing cis- and trans-isomers. A similar result is obtained by double dehydrohalogenation, subsequent hydrolysis of esters of the general formula III, where P is methyl or ethyl, and anodicization of the reaction mixture (see, for example, K. Kondo et al., Pest. Bci. 11, 180, 1960; K. Matsui et al., Bull. Chem. Boo. Jpn. 59, 221, 1986). Since known synthetic procedures do not allow for the direct, technically feasible synthesis of even relatively pure cis-permethrin acid, procedures are being sought that allow for the additional separation of the cis-trans isomeric mixture of permethrin acid, or their suitable derivatives.

A known process is the traction crystallization and fractional distillation of the cis-trans isomeric mixture of permethrin acid (see, for example, Coll. Czech. Chem. Commun. 24. 2230, 1959, IE I 570 557 · DB 199 725). Other known processes are based on the traction precipitation of cis-permethrin acid or its salt with an amine from a solution of soluble cis-trans-isomeric salts of permethrin acid (for example, KP 0 003 060 and EP 00 110 875). However, it is clear from the published data that the aforementioned processes are technically unsatisfactory and that they only result in incomplete separation of the cis-trans-isomers.

The above-mentioned shortcomings are solved by the method of preparing the crystalline sodium salt of cis-permethrin acid of formula I according to the invention, which consists in treating the sodium salt of 2,2-dimethyl-3-/2,'2,'2-trichloroethyl/cyclopropanecarboxylic acid of formula II in the cis or cis and trans configuration with sodium hydroxide in water, optionally in the presence of an inert organic solvent from the group of aliphatic or aromatic hydrocarbons such as hexane, xylene, toluene and optionally in the presence of sodium halide at a temperature of 70 to 100 °C, then the reaction mixture is cooled to a temperature of -20 to +20 °C and the crystalline precipitate of sodium salt of cis-permethrin acid formed by standing is separated by suction, filtration, decantation or centrifugation and optionally recrystallized from a mixture of water and an inert, water-miscible organic solvent.

The crystalline sodium salt of cis-permethrin can also be prepared according to the invention, the essence of which consists in treating the 4,6,6,6-tetrahydro-3,3-dimethylhexanoic acid ester of the general formula III, where B is methyl or ethyl, with sodium hydroxide in an inert organic solvent from the group of aliphatic or aromatic hydrocarbons, such as hexane, xylene, toluene, first in the absence and then in the presence of water at a temperature of -10 to 100 ° C, then the reaction mixture is optionally cooled to a temperature of -20 to +20 ° C and the crystalline precipitate of the cis-permethrin salt formed by standing is separated. Optionally, it can be recrystallized from a mixture of inert water and a water-miscible organic solvent.

Crystalline sodium salt of cis-permethrin acid can also be prepared by the action of sodium hydroxide on cis- or cis- and trans-permethrinic acid of formula IV in water or in a mixture of water and an inert organic solvent at a temperature of 20 to 90 °C, then the mixture is cooled to a temperature of -20 to 20 °C and the precipitated crystalline precipitate of the cis-permethrinic acid salt is separated and optionally recrystallized.

The methods according to the invention utilize the hitherto unknown different solubilities of the cis-trans isomeric sodium salts of permethrin acid in water, or in a mixture with an inert, water-miscible organic solvent. The crystalline salt of cis-permethrin acid is preferentially precipitated from their concentrated solution. It has further been found that

CS 269 408 Bl if the aodification is not carried out in the above-described processes, or is carried out only partially, instead of the free, isomerically unresolvable permethrin acid isomerηδ, the pure crystalline sodium salt of cis-permethrin acid is precipitated, which is then simply mechanically separated and optionally recrystallized. Free cis-permethrin acid can be prepared from the sodium salt thus obtained by processes known per se.

The advantage of the new process is its technical simplicity, surprisingly high efficiency compared to the known separation processes mentioned above and its easy integration into the production process for the preparation of cis-permethrin acid. Another advantage of the invention is that the sodium salt of cis-permethrin acid can also be directly used for the synthesis of insecticidally active esters, without prior isolation of free cis-permethrin acid.

The essence of the invention and the method of its use are explained in more detail in the following examples, which, however, do not limit the scope of the invention in any way.

Example 1

Preparation of sodium cis-permethrinate from a cis-trans isomeric mixture of permethrin acid. The example documents the effect of solvent on the yield and purity of the product.

Into a 21-liter three-necked flask equipped with a stirrer, thermometer and reflux condenser, placed on a heating nest, were introduced 614 ml of a 35% toluene solution of permethrin acid (90.9% cis : 9.1% trans) and 100 ml of water. While stirring, 54 ml of a 46% aqueous sodium hydroxide solution were rapidly added. The temperature of the reaction mixture, which thickened with the precipitated sodium salt gel, spontaneously rose to 46 °C. Further heating to 80 to 85 °C resulted in the dissolution of the salt, forming a homogeneous aqueous phase. The mixture was stirred intensively for 5 min., the organic phase was separated. Aliquots (10 g of the aqueous phase) were taken for crystallization experiments. The crystallization time was always 48 h., the mother liquors were sharply suctioned off, the filter cake was freely dried in air. The sodium permethrinate content was determined by titration. The sodium permethrinate content in the starting aqueous solution was found to be 52.2% by weight.

Table

aliquot. no. water (ml) acetone (ml) temperature (°C) weight (g) cis:trans 1 *· 10 +3 3.37 98.6 : 1.4 2 - 20 +3 3.89 98.9 : 1.1 3 - 30 +3 4.00 98.9 : 1.1 4 - 40 +3 4.17 98.6 : 1.4 5 3 30 +3 2.96 99.0 : 1.0 6 3 50 +3 3.45 98.8 : 1.2 7 - 60 +3 4.44 98.8 : 1.2 8 - 50 +15 3.87 97.9 : 2.1 +/ ' In your mentioned experiments it was permethrin content sodium in product higher than

98.6%.

Example 2

Preparation of sodium cis-permethrinate from 2,2-dimethyl-3~/2^2'2-trichloroethyl/cyclopropan.carboxylic acid /11/

1,433 g of 10% aqueous sodium hydroxide solution were introduced into a 61 cm2 round bottom flask equipped with a Teflon stirrer and a thermometer, and 1,410 ml of a xylene solution of trichloroacetic acid of formula XI (245 g, isomer content 85% cis-, 15% trans) were added dropwise, and the reaction mixture was refluxed for 90 min with stirring. After cooling to 35 °C, the aqueous layer was

CS 269 408 Bl

separated, washed with 300 ml of xylene and allowed to crystallize at a temperature of 0 to -5 °C. The precipitated cryothallic salt of cia-permethrin acid was filtered off with suction and evaporated. Yield 210 g of crude product, which was further processed according to the procedure described in Example 3.

Example 3

Preparation of free olia-permethrin acid

To the sodium salt of cia-permethrin acid from example 2 was added 800 ml of boiling water. After the solution had cooled, 500 ml of diochloroethane and 100 ml of con. hydrochloric acid were added. After phase separation, the aqueous layer was repeatedly washed with dichloroethane (2x 150 ml). The combined organic extracts were filtered and evaporated under water pump vacuum. 180 g of permethrin acid containing 98% by weight, cis- and 2% by weight, trans-isomer (impurity content 1%) was obtained.

Example 4'

Control experiment

The procedure was as in Example 2, but instead of separating the sodium salt of permethrin acid, the reaction mixture was acidified with excess hydrochloric acid (conc.). The crude permethrin acid obtained contained 87 wt.% of the cis-isomer, 8 wt.% of the trans-isomer and 5 wt.% of impurities.

Example 5

Control experiment

Crystallization of 5 g of crude permethrin acid from Example 4 from n-heptane yielded 3.9 g of acid containing 94 wt.% of cis-isomer, 4 wt.% of trans-isomer and 2 wt.% of impurities.

Example 6

Preparation of sodium cis-permethrinate from the methyl ether of the acid of formula III

The methyl ester of the acid of formula III was dehydrohalogenated with excess sodium tert-butylate in a hexane/t-butanol/dimethylacetamide mixture at -5°C and then hydrolyzed with concentrated aqueous sodium hydroxide. The aqueous layer was separated, carefully acidified to pH 9.3 and 9.7 and placed in a refrigerator. The precipitated crystalline salt of cis-permethrin acid was filtered off with suction and dried. Yield 80%; isomeric composition 97% by weight of cis-isomer, 3% by weight of trans-isomer.

Example 7

Control experiment /

The procedure of Example 6 was followed, but instead of separating the sodium salt, the reaction mixture was acidified with excess hydrochloric acid to a strongly acidic reaction. The obtained permethrin acid (87% yield) contained 78% by weight of the cis- and 22% by weight of the trans-isomer.

Example 8

Use of sodium cis-permethrinate to prepare an inaecticidally effective ester

0.486 g (2.1 mmol) of sodium cis-permethrinate, 0.725 g (1.91 mmol) of 0.003 g (0.009 mmol) of cis-permethrinate, 0.003 g (0.009 mmol) of tetrabutylammonium bromide, 2 ml of toluene and 1 ml of water were weighed into a 25 ml flask and the reaction mixture was stirred vigorously for 6 hours at a temperature of 70 °C. After cooling, the toluene layer was separated and washed successively with 1 ml of an aqueous solution of 5% by weight of sodium carbonate and 1 ml of water. After evaporation and drying in vacuo, 0.73 g (92% of theory) of cis-permethrin acid <2-cyano-/3-phenoxy/-benzyl ester, exhibiting a significant insecticidal effect, was obtained.

Claims (4)

SUBJECT OF THE INVENTION ' 1. Crystalline sodium salt of o-permethrinic acid of formula I. 2. A method for preparing the crystalline sodium salt of cis-permethrin acid of formula I according to point 1, characterized in that the sodium salt of 2,2-dimethyl-3-[2,'2,'2-trichloroethyl]cyclopropanecarboxylic acid of formula II in the cis or cis and trans configuration is treated with sodium hydroxide in water, optionally in the presence of an inert organic solvent from the group of aliphatic or aromatic hydrocarbons, such as hexane, xylene, toluene and optionally in the presence of sodium halide at a temperature of 70 to 100 °C, then the reaction mixture is cooled to a temperature of -20 to +20 °C and the crystalline precipitate of sodium salt of cis-permethrin acid formed by standing is separated by suction, filtration, decantation or centrifugation and optionally recrystallized from a mixture of water - inert water-miscible organic solvent. 3. A method for preparing the sodium salt of formula I according to point 1, characterized in that the 4,6,6,6-tetrachloro-3,3-dimethylhexanoic acid ester of general formula III, where R is methyl or ethyl, is treated with sodium hydroxide in an inert organic solvent from the group of aliphatic or aromatic hydrocarbons, such as hexane, xylene, toluene, first in the absence and then in the presence of water at a temperature of -10 to 100 °C, then the reaction mixture is optionally cooled to a temperature of -20 to +20 °C and the crystalline precipitate of the salt of formula I that has separated on standing is separated by suction, filtration, decantation or centrifugation and optionally recrystallized from a mixture of water - an inert water-miscible organic solvent. 4. A method for preparing the sodium salt of formula I according to point 1, characterized in that permethrin acid of formula IV in the cis- or cis- and trans- configuration is treated with sodium hydroxide in water or in a mixture of water - inert organic solvent at a temperature of 20 to 90 °C, then the mixture is cooled to a temperature of -20 to +20 °C and the precipitated crystalline precipitate of the cis-permethrin acid salt is separated by suction, filtration, decantation or centrifugation and optionally recrystallized from the mixture of water - inert organic solvent. .