PROCESS FOR THE PREPARATION OF ALKYL-THIONO-PHOSPHONIC ACID DICHLORIDES

1,184,767. Alkylthionophosphonic acid dichlorides. FARBENFABRIKEN BAYER A.G. 24 Oct., 1968 [21 Nov., 1967], No. 50543/68. Heading C2C. An alkylthionophosphonic acid dichloride of the formula R.P(S)Cl 2 in which R is an alkyl radical is obtained by heating a complex compound formed from an alkyl halide, PCl 3 and aluminium chloride with a di(C 1 -C 4 alkyl) disulphide as sulphur donor in the presence of an alkali metal chloride or ammonium chloride. The reaction is suitably carried out as a " onepot process," the alkyl halide being introduced with vigorous stirring, or dropwise, into a mixture of the aluminium chloride and PCl 3 to form the complex, the alkali metal chloride or ammonium chloride then added followed by the dialkyl disulphide, and the mixture being finally heated, preferably to 190-220‹ C. Examples are given for the production of the dichlorides in which R is methyl, ethyl and isopropyl respectively, using dimethyl disulphide as the dialkyl disulphide in each case.