DE1143200B - Process for the preparation of thionophosphonic acid esters - Google Patents

Description

Process for the production of thionophosphonic acid esters Addition to patent 1,099,530 The subject of the main patent is a process for the production of chlorine-substituted alkylthionophosphonic acid-O-alkyl-O-phenyl esters of the general formula in which R and R1 is an alkyl radical and R2 is a chlorine-substituted phenyl radical, characterized in that an alkylthionophosphonic acid O-alkyl ester chloride is reacted with a chlorinated phenol in a manner known per se.

According to the information in the cited patent, the there stand out compounds described by a good insecticidal effectiveness at low Warm-blooded toxicity.

It has now been found that thionophosphonic acid 0- (2-chloro-4-tert-butylphenyl) ester of the general formula in which R1 and R2 stand independently of one another for methyl or ethyl radicals, have excellent insecticidal properties and are therefore particularly suitable as pesticides.

These compounds are produced in an analogous manner to described in the main patent, according to methods known per se, d. H. through implementation of thionophosphonic acid chlorides with the sodium salt of 2-chloro-4-tert.-butylphenol.

The reaction of the present invention is conveniently carried out using a inert organic solvent such as benzene or acetonitrile performed.

Furthermore, it is particularly pure in order to achieve good yields Process products advantageous the implementation according to the process at weak to moderate make elevated temperature and also the reaction mixture after combination the starting components are reheated for some time with stirring.

The thionophosphonic acid-O- (2-chloro-4-tert. -butylphenyl) esters are colorless oils, most of which do not decompose in a high vacuum let distill.

As already mentioned above, the process products cause their insecticidal properties are valuable pesticides are intended to be used primarily in crop protection.

The relatively low toxicity to warm blooded animals is particularly advantageous of the connections, which enables safe handling of the same in practice.

In addition, the thionophosphonic acid esters according to the invention have also a pronounced systemic effectiveness against ectroparasites on living Large animals such as B. cows or sheep.

The following examples illustrate the claimed process: Example 1 A solution of 94 g (0.5 mol) of 2-chloro-4-tert-butylphenol (boiling point = 68 to 69 "C) in 200 cc of methanol is added with stirring to a sodium methylate solution which contains 1 mol of sodium in dissolved form , the reaction mixture is then treated with 200 cc of benzene and then the solvents are removed by azeotropic distillation. The remaining sodium salt of 2-chloro-4-tert-butylphenol is dissolved in 200 cc of acetonitrile. To this solution is now added with stirring at 30 to 40 "C 80 g (0.5 mol) of ethyl-thionophosphonic acid-O-methyl ester chloride (boiling point = 44" C), the reaction mixture is then heated to 40 "C for another hour and then poured into 500 cc of ice water. The oil which has separated out is taken up in benzene, and the benzene solution is washed with water until it reacts neutral, separated off and dried. In the subsequent fractional distillation, after evaporation of the solvent, 88 g (580/0 of theory) of the ethylthionophosphonic acid O-methyl-0- (3-chloro-4-tert-butylphenyl) ester of b.p.o.o1 = ll50C.

The mean toxicity (Das) of the compound is in the rat per os 500 mg per kilogram of animal.

Example 2 In a manner analogous to Example 1, from 94 g (0.5 mol) of 2-chloro-4-tert-butylphenol and 87 g of ethylthionophosphonic acid O-ethyl ester chloride (b.p. 1 = 48 "C) 105 g (65 ° / o the theory) Ethylthionophosphonic acid - 0 - ethyl - 0 - (2 - chloro - 4 - tert-butylphenyl) ester of Kp.ool = 1190 C.

The compound shows moderate toxicity in the rat per os of 100 mg per kilogram of animal.

Example 3 Under the same reaction conditions as in Example 1, from 94 g (0.5 mol) of 2-chloro-4-tert-butylphenol and 80 g of methylthionophosphonic acid O-ethyl ester chloride (b.p. 12 = 60 ° C) 116 g (760 / o the theory) of the methylthionophosphonic acid O-ethyl-0- (2-chloro-4-tert-butylphenyl) ester of boiling point oi 112 "C.

Average toxicity (DL50) of the compound: 250 mg per kilogram of rat for oral application.

Example 4 By reacting 94 g (0.5 mol) of 2-chloro-4-tert-butylphenol and 73 g of methylthionophosphonic acid O-methyl ester chloride (bp 12 = 500 ° C.) under the conditions given in Example 1, 88 g (6O0 / o of theory) of the methylthionophosphonic acid O-methyl-0- (2-chloro-4-tert-butylphenyl) ester of boiling point o1 = 111 "C.

The mean toxicity (DL50) of the compound is in the rat 250 mg per os per kilogram of animal.

Claims (1)

PATENT CLAIM: Process for the production of thionophosphonic acid esters in continuation of the main patent 1 099 530, characterized in that here alkylthionophosphonic acid 0-alkyl ester chlorides of the general formula in which R1 and R2 independently represent methyl or ethyl radicals, with the sodium salt of 2-chloro-4-tert-butylphenol in a manner known per se to form compounds of the general formula in which R1 and R2 have the meaning given above, are reacted.