PROCESS FOR PREPARING ALKYL OR ARYL THIOPHOSPHORUS HALIDES AND MIXED ISOMERS THEREOF

IMPROVED PROCESS FOR PREPARING ALKYL OR ARYL THIOPHOSPHORUS HALIDES AND MIXED ISOMERS THEREOF Improved yields and a lower accumulation of by-product is obtained in the method for preparing compounds of the formula: wherein R is a C1 to C20 alkyl radical, cycloalkyl of 5-6 carbon atoms in the ring and the C1-C4 alkyl substituted derivative thereof, an aralkyl radical of up to two fused rings, the alkyl portion having from 1 to 20 carbon atoms, an aryl radical of up to three fused rings and the C1-C4 alkyl derivatives thereof, and biphenyl and the C1-C4 alkyl derivatives thereof, X is a halogen of chlorine or bromine, and Z is either R or X, by the reaction of a phosphorus halide source, a hydrocarbon source selected from the group consisting of RH, RX and RSaR, wherein a is 1 or 2 and a sulfur source under autogenous pressure in an autoclave at a temperature ranging from about 175.degree.C. to about 450.degree.C. by recycling to successive runs a by-product of the reaction remaining after separation of the RP(S)XZ product fraction selected from the group consisting of:a) a by-product fraction having a boiling point lower than the product fraction;b) a by-product fraction having a boiling point higher than the product fraction;c) a by-product fraction having a boiling point higher than the product RP(S)XZ wherein Z is R fraction;d) XZP(S)RP(S)XZe) liquid residue;f) solid residue;g) mixtures thereof; andh) mixtures of the preceding with R2P(S)X wherein R and X are as defined hereinbefore.