Improvements in or relating to a process for the preparation of dialkoxythiophosphoryl chlorides

摘要

Dialkoxythiophosphoryl monochlorides of formula FORM:0692169/IV (b)/1 wherein R1 and R2 are alkyl groups of 1 to 8 C atoms are made by treating a corresponding monoalkoxythiophosphoryl dichloride with a solution of an alkali metal hydroxide in an alkanol containing 1 to 8 C atoms per molecule. It is stated that anhydrous conditions are required only when preparing the monoalkoxy thiophosphoryl dichloride from thiophosphoryl chloride and in the process of the invention minor amounts of water may be present. Preferably an excess of alkanol is used as a reaction medium. At least a molar proportion, preferably 1.05-1.5 mols, of hydroxide is used per mol. of dichloride. The preferred temperature range is about -10 DEG to +25 DEG C. The monochlorides are used in the preparation of O,O-dialkyl - O - p - nitrophenyl thiophosphates and for this purpose they need not be isolated, the reaction product being treated with an alkali metal p-nitrophenate whilst dissolved in the excess alkanol. The monoalkoxythiophosphoryl dichloride may be made by reacting one mol. of thiophosphoryl chloride with approximately one mol. of an alkali metal alcoholate in an anhydrous alcoholic medium, preferably at -10 DEG to +25 DEG C., or preferably by reacting one mol. of thiophosphoryl chloride with approximately one mol. of a substantially anhydrous alkanol at -10 DEG to +25 DEG C. and removing hydrogen chloride until the reaction is substantially complete and thereafter removing hydrogen chloride at a temperature not exceeding about 50 DEG C. In examples, thiophosphoryl chloride is treated with (1) anhydrous ethanol to form ethoxythiophosphoryl dichloride which is treated with ethanolic sodium hydroxide to yield diethoxythiophosphoryl chloride; (2) anhydrous methanol to yield methoxythiophosphoryl dichloride which on treatment with methanolic sodium hydroxide yields dimethoxythiophosphoryl chloride; (3) sodium butylate in anhydrous butanol to yield butoxythiophosphoryl dichloride which on treatment with butanolic sodium hydroxide yields dibutoxythiophosphoryl chloride; (4) anhydrous n-hexanol to yield hexoxy-thiophosphoryl dichloride which on treatment with potassium hydroxide in n-hexanol yields dihexoxythiophosphoryl chloride; (5) sodium 2-ethylhexylate in anhydrous 2-ethylhexanol and the product treated without isolation with sodium hydroxide in 2-ethylhexanol to yield di-2-ethylhexoxythiophosphoryl chloride and in (6) methoxy- or ethoxy-thiophosphoryl dichlorides are respectively treated with ethanolic or methanolic sodium hydroxide to yield methoxyethoxythiophosphoryl chloride.