GB2169293A

GB2169293A - Process for the preparation of pyrethroids

Info

Publication number: GB2169293A
Application number: GB08600243A
Authority: GB
Inventors: Dr Gergely Heja; Dr Dezso Korbonits; Endre Palosi
Original assignee: Chinoin Gyogyszer es Vegyeszeti Termekek Gyara Zrt
Current assignee: Chinoin Private Co Ltd
Priority date: 1985-01-08
Filing date: 1986-01-07
Publication date: 1986-07-09
Also published as: FR2575746B1; GB8600243D0; GB2169293B; FR2575746A1; HUT39077A

Abstract

Compounds of the general formula (I> <IMAGE> - wherein R is halogen or C1-4 alkyl - are prepared by reacting a compound of the general formula (II> <IMAGE> - wherein R is as given above - with an alkali phenolate of the general formula (III> <IMAGE> in the presence of copper and/or copper(I)-salt catalyst.

Description

SPECIFICATION Process for the preparation of pyrethroids The present invention is directed to a new process for the preparation of the compounds of the general formula (I)

- wherein R stands for halogen or alkyl containing 1 to 4 carbon atoms -the compounds of the general formula (I) are significant selective insecticides.

Several processes are known for the preparation of said compounds. All of them are characterized by forming an ester group with a diphenyl ether derivative and after the formation of the ester group the additional conversion is exclusively conducted on the acid component. (GB P. No. 1 413 491 and 1 438 129; USP 4255351 and 4289711 and DE OS Nos. 2 716 771,2 437 882,2 651 341).

Although it would have been obvious to form the ether group in the last step by the substitution of the bromine atom of the ester of the general formula (II)

wherein R stands as given above - (J. Agric. Food. Chem. 29, 1118 /1981/) which ester can be obtained almost quantitatively from 3-bromo-benzylal:ohol and permethric acid chloride the benzyl alcohol being economically and simply prepared from benzaldehide instead of diphenyl ether, it could not be expected that the reaction could be conducted successfully without the change of the molecules of the general formula (II).

Diphenyl ethers can be prepared by Ullmann reaction in alkaline medium at a relatively high temperature in the presence of heavy metals or metal salts (copper). Under the conditions of the Ullmann reaction according to the state of art one could not hope that the dichloro vinyl and the ester group remain intact. We have surprisingly found that the ester of the general formula (II) can be converted to an ether of the general formula (I) with an excellent yield under heating with an alkali phenolate of the general formula (III)

in the presence of copper and/or copper salt catalyst.

Accordingly the present invention is directed to the preparation of esters of the general formula (I)

-wherein R stands for halogen atom or C14 alkyl -by reacting a compound of the general formula (II)

-wherein R stands as given above - with an alkali phenolate of the general formula (III)

preferably in the presence of copper powder and/or copper(l)-salt catalyst and optionally in the presence of an organic base at a temperature of 120-180 C in an organic solvent and/or diluent.

The formation of the ether of the general formula (I) is preferably performed with potassium phenoiate preferably at 135-155"C and by using as catalyst copper powder activated by iodine and pyridine and using xylene as a solvent or diluent.

Further details of the present invention are illustrated by the following Examples without limiting the scope of the invention to the Examples.

Example 1 20.9 g. (0.1 mole) 2-(2,2-dichloro-vinyl)-3,3-dimethyl-cyclopropane-carboxylic acid are dissolved in 50 ml. benzene and to the solution 0.5 ml. of pyridine are added and under stirring at room temperature 7.6ml. (0.105 mole) thionyl chloride are added dropwise within 30 minutes. When the gas evolution becomes slower the mixture is heated under reflux for 3 hours. The reaction mixture is then evaporated in vacuo. The residue is dissolved in 25 ml. of pyridine and a solution of 18.7 g. (0.1 mole) 3-bromo-benzylalcohol in 25 ml. pyridine is added dropwise under stirring at 15-20"C within 30 minutes. The mixture is then further stirred for 4 hours at room temperature and filtered.The filtrate is evaporated in vacuo, 36.68 g. (97%) 3-bromo-benzyl-2-(2,2-dichloro-vinyl)-3,3-dimethyl-cyclo-propane-carboxylate are obtained.

Example 2 5.18 g.(0.055 mole) phenol, 3.31 g. (0.05 mole 85%) potassium hydroxide, 18 ml. xylene are stirred and heated by using a water condenser until the termination of the water condensation. The mixture is then cooled to 100"C and 0.16 g. copper powder activated with iodine, and 0.5 ml. pyridine are added whereafter a solution of 18,9 g. (0.05 mole) 3-bromo-benzyl-2-(2,2-dichloro-vinyl )-3,3-dimethyl-cyclopropane- carboxylate in 5 ml. xylene are added dropwise within 10 minutes. The reaction mixture is then heated for 6 hours under stirring under reflux. After cooling the reaction mixture is filtered, the filtrate is washed with 2 x 20 ml. 10% sodium hydroxide solution, treated with perlite, filtered, evaporated in vacuo and purified, eluted with benzene on a silicagel column.Thus 16.95 g. (86%) 3-phenoxy-benzyl-2-(2,2-dichloro vinyl)-3,3-dimethyl-cyclopropane-carboxylate (la) are obtained, the product being identical in its physicochemical properties and in all spectroscopical date with the substance prepared by known method.

Example 3 14.9 g. (0.05 mole) 2-(2,2-dibromo-vinyl)-3,3-dimethyl-cyclopropane-carboxylic acid are dissolved in 30 ml. benzene and to the solution 0.2 ml. pyridine are added and under stirring 3.8 ml. thionyl-chloride are added dropwise at room temperature. The mixture is then heated for 3 hours under reflux and evaporated in vacuo. The residue is dissolved in 15 ml. pyridine and under stirring at 20"C a solution of 9.35 g.

(0.05 mole) 3-bromo-benzylalcohol in 10 ml. pyridine is added dropwise within 30 minutes. The mixture is stirred for 4 hours at room temperature then filtered and the filtrate is evaporated. 21.71 g. (93%) 3 bromo-benzyl-2-(2,2-dibromo-vinyl)-3,3-dimethyl-cyclopropane-carboxylate are obtained. 5.18 g. (0.055 mole) phenol, 3.08 g. (0.046 mole 85%) potassium hydroxide and 20 ml. xylene are heated under stirring equipped with a water trap until the termination of water condensation. The mixture is then cooled back below 100"C and 0.15 g. of copper powder activated with iodine and 0.5 ml. pyridine are added, and within 10 minutes a solution of the above prepared 3-bromo-benzyl-2-(2,2-dibromo-vinyl)-3,3-di-methyl cyclopropane carboxylate in 10 ml. xylene is added. The reaction mixture is heated under stirring for 5 hours, cooled and filtered. The filtrate is washed with 2 x 20 ml. 10% sodium hydroxide in vacuo. The residue is purified on silica gel column and eluted with benzene. Thus 17.64 g. (79%) 3-phenoxy-benzyl-2 (2,2-dibromo-vinyl)-3,3-dimethyl-cyclopropane-carboxylate are obtained and the spectroscopical data of the product are identical with the product obtained by known method.

Example 4 16.82 g. (0.1 mole) 2-(2,2-dimethyl-vinyl)-3,3-dimethyl-cyclopropane-carboxylic acid are dissolved in 50 ml. benzene and to the solution 0.5 ml. pyridine is added and under stirring at room temperature 7.6 ml.

thionyl chloride are added dropwise. The mixture is then heated for 3 hours and evaporated in vacuo.

The residue is dissolved in 25 ml. pyridine and under stirging at 20"C 18.7 g. 3-bromo-benzyl-alcohol dissolved in 25 ml. pyridine is added dropwise within 30 minutes. The reaction mixture is stirred for 4 hours at room temperature, filtered and the filtrate is evaporated. 32.38 g. (96 %) 3-bromo-benzyl-2-(2,2dimethyl-vinyl)-3,3-dimethyl-cyclopropane-carboxylate are obtained.

5.18 g. (0.055 mole) phenol, 3.31. g. (0.05 mole) 85%) potassium hydroxide and 20 ml. xylene are heated under stirring with a water trap until the termination of the water condensation. The mixture is cooled back below 100"C and 0.16 g. copper powder activated with iodine as well as 0.5 ml. pyridine are added and within 10 minutes 16.86 g. (0.05 mole) 3-bromo-benzyl-2-(2,2-dimethyl-vinyl)-3,3-dimethyl-cy- clopropane carboxylate in 10 ml. xylene are added dropwise. The reaction mixture is then heated under stirring with 2 x 20 ml. 10% sodium hydroxide solution, treated with perlite, filtered and evaporated in vacuo. The residue is eluted with benzene on a silica gel column and thus 15.24 g. (87)%) 3-phenoxybenzyl-2-(2,2-dimethyl-vinyl)-3, 3-dimethyl-cyclopropane-carboxylate are obtained and the spectroscopical data of the product are identical with those prepared by known method.

Claims

1. Process for the preparation of the compounds of general formula (I)

-wherein R stands for halogen or CIA alkyl -which comprises reacting a compound of the general formula (II)

- wherein R is as given above - with alkali phenolate of the general formula (III)

in the presence of copper and/or copper(l)-salt catalyst.

2. A process as claimed in claim 1, which comprises conducting the reaction with potassium phenolate and in the presence of a copper catalyst preferably copper powder activated with iodine.

3. Process as claimed in any of claims 1 or 2 which comprises preforming the ether formation in the presence of a catalytical amount of pyridine.

4. A process as claimed 1 to 3 which comprises performing the reaction in an aprotic organic solvent, preferably in the presence of xylene.

5. A process as claimed in any of claims 1 to 4 which comprises performing the ether formation at 120-180, preferably 135-155"C.