Esters phosphoniques et leur procédé de production

The invention comprises phosphonic acid esters of the general formula: wherein R and R1 represent alkyl (preferably C1-4) or aryl (preferably phenyl) radicals, Ar represents an aryl (preferably phenyl) radical, R2 represents a C1-4 alkyl radical, X represents oxygen or sulphur, and n is 0, 1 or 2. They are prepared by reacting phosphonic- or thionophosphonic acid halides, especially chlorides, with suitable substituted phenols. Suitable phosphonic acid halides include methyl, ethyl and propyl phosphonic acid ethyl ester chlorides; phenyl, p-chlorophenyl and 3,4-dichlorophenyl phosphonic acid ethyl esters chlorides; also the corresponding thionophosphonic acid derivatives and other alkyl esters such as the methyl, propyl and butyl esters. Suitable phenols include alkylmercaptophenols, phenylmercaptophenols, alkylmercaptocresols, 2-ethylmercapto - p - chlorophenol, 2 - methyl - mercapto - p - chlorophenol, 2 - phenylmercapto - p-chlorophenol; also the corresponding sulphoxides and sulphones. In the case of preparing the sulphoxides or sulphones, the mercaptophenyl phosphonic acid products may be oxidized thereto. The phosphonic ester halides are generally reacted with salts of the phenols, especially alkali metal salts such as the sodium or potassium salt or with the phenols in the presence of acid binding agents especially alkali metal alcoholates, hydroxides or carbonates. The reaction temperature is generally 0-100 DEG C. although higher or lower temperatures may be used. Generally, the reaction is started at a relatively low temperature or at room temperature and completed on the steam bath. The presence of inert solvents is desirable, e.g. acetone, lower alcohols such as methanol or ethanol, benzene or toluene. The compounds are insecticides and plant-protecting agents. Examples describe the preparation from the appropriate phenol or a salt thereof and phosphonic ester chloride of: (1) ethyl p-methylmercaptophenyl methylphosphonate; (2) ethyl p-methyl-sulphinylphenyl methylphosphonate; (3) ethyl p-methylsulphonylphenyl methylphosphonate; (4) ethyl o-methylmercaptophenyl methylphosphonate; (5) o-ethylmercaptophenyl iso-propyl methylphosphonate; (6) ethyl p-methylmercaptophenyl methylthionophosphonate; (7) methyl p-methylmercaptophenyl methylthionophosphonate; (8) methyl p-methylsulphinylphenyl methylthionophosphonate; (9) methyl p-methylsulphonylphenyl methylthionophosphonate; (10) p-ethylmercaptophenyl methyl methylthionophosphon