Patent ID: 7049456

Claim:
A method of preparing an O,O-dialkyl S-[2-(alkylthio)alkyl] phosphorodithioate having the formula wherein each R 1 is independently C 1 –C 4 alkyl, R 2 is C 1 –C 4 alkylene, and R 3 is C 1 –C 4 alkyl, comprising (a) treating an O,O-dialkyl dithiophosphoric acid of the formula: wherein each R 1 is independently C 1 –C 4 alkyl, with a base in the substantial absence of organic solvent to obtain an O,O-dialkyl dithiophosphoric acid salt of the formula: wherein each R 1 is independently C 1 –C 4 alkyl, and X is a cation, and (b) reacting the O,O-dialkyl dithiophosphoric acid salt with a thioalcohol derivative having the formula: R 3 —S—R 2 —Y wherein R 2 is C 1 –C 4 alkylene, R 3 is C 1 –C 4 alkyl, and Y is a leaving group.