Nouveaux composés et nouvelles compositions insecticides

摘要

The invention comprises dimethyl-2-chloro-1-(dihalophenyl) vinyl phosphates having the general formula wherein R represents the group They are prepared by reacting trimethyl phosphite with the appropriate tetrahaloacetophenone. The reaction is preferably carried out by slowly adding at a temperature between 40 DEG and 60 DEG C. the approximately stoichrometric quantity of trimethyl phosphite to the appropriate tetrahaloacetophenone, followed by heating at a temperature between 90 DEG and 110 DEG C. The product generally crystallizes from the reaction mixture on cooling. It may be purified by washing with a suitable solvent, e.g. pentane, or by crystallization from a suitable solvent or mixture of solvents, e.g. ether-ligroin or ether-pentane. Examples are given for the production of dimethyl 2 - chloro - 1 - (2,4 - dichlorophenyl) vinyl phosphate, dimethyl 2-chloro-1-(4-chloro-2-bromophenyl) vinyl phosphate and dimethyl 2 - chloro - 1 - (2,5 - dichlorophenyl) vinyl phosphate. The products are useful as pesticides (see Division A5). The tetrahaloacetophenones used as starting materials may be prepared by reacting dichloro-acetyl chloride with the appropriate dihalobenzene in the presence of aluminium chloride in a conventional manner when 2,2,41-trichloro-21 -bromoacetophenone is prepared in this manner the bromine atom and possibly the chlorine atom are found to be labile. So that the crude product is a mixture of isomers. Specification 888,648 is referred to.ALSO:An insecticidal composition comprises as active ingredient a dimethyl 2-chloro-1-(dihalophenyl) vinyl phosphate of the formula where R represents the group (see Division C2), together with a solid or liquid carrier and/or a surface active agent and/or a compressed gas. Other insecticidally active materials may be present such as pyrethrum, rotenone sabadilla, DDT (Trade Mark), benzene hexachloride, thiodiphenyl amine, cyanides, tetraethyl pyrophosphate, diethyl p-nitrophenyl thiophosphate, azobenzene, dimethyl 2, 2-dichlorovinyl phosphate, dimethyl 1, 2-dibromo-2, 2-dichlorethyl phosphate and various compounds As, Pb and/or F. Suitable adjuvants, such as spreading or wetting agents, which may be present include alkylaryl sulphonates, alkyl sulphonates containing at least 10 carbon atoms, phenolethylene oxide condensates, and C12-C20 amines and ammonium salts. Insects are controlled by subjecting the insects to the effect of a compound of the above general formula or a composition containing such a compound. Crop yields may be improved by applying one or more of the compounds or compositions specified above to a crop area before or after crop planting, or before or after crop emergence. Specification 888,648 is referred to.