AbstractThiophosphate and phosphate esters have been synthesized in great variety since about 1945, and are being produced in increasing quantities, mainly for plant protection. An important property of alkyl phosphates and thiophosphates is their alkylating power, which is comparable with that of dialkyl sulfates and alkyl p‐toluenesulfonates. The chemistry of thiophosphates is largely determined by their alkylating properties, since the sulfur, both in the alkyl thiophosphate and in the thiophosphate anion formed on dealkylation, can act as a point of attack for self‐alkylation.