Thiophosphoryl chloride

Synthesis

Thiophosphoryl chloride can be generated by several reactions starting from phosphorus trichloride. The most common and practical synthesis, hence used in industrial manufacturing, is directly reacting phosphorus trichloride with excess sulfur at 180 °C.

PCl₃ + S → PSCl₃

Using this method, yields can be very high after purification by distillation. Catalysts facilitate the reaction at lower temperatures, but are not usually necessary. Alternatively, it is obtained by combining phosphorus pentasulfide and phosphorus pentachloride.

3 PCl₅ + P₂S₅ → 5 PSCl₃

Reactions

PSCl₃ is soluble in benzene, carbon tetrachloride, chloroform, and carbon disulfide. However, it hydrolyzes rapidly in basic or hydroxylic solutions, such as alcohols and amines, to produce thiophosphates. In water PSCl₃ reacts, and contingent on the reaction conditions, produces either phosphoric acid, hydrogen sulfide, and hydrochloric acid or dichlorothiophosphoric acid and hydrochloric acid.

PSCl₃ + 4 H₂O → H₃PO₄ + H₂S + 3 HClPSCl₃ + H₂O → HOP(S)Cl₂ + HCl

PSCl₃ is used to thiophosphorylate, or add P=S, organic compounds. This conversion is widely applicable for amines and alcohols, as well as amino alcohols, diols, and diamines. Industrially, PSCl₃ is primarily used to produce insecticides, like parathion.

PSCl₃ + 2 C₂H₅OH → (C₂H₅O)₂PSCl + 2 HCl(C₂H₅O)₂PSCl + NaOC₆H₄NO₂ → (C₂H₅O)₂PSOC₆H₄NO₂ + NaCl

PSCl₃ reacts with tertiary amides to generate thioamides. For example:

C₆H₅C(O)N(CH₃)₂ + PSCl₃ → C₆H₅C(S)N(CH₃)₂ + POCl₃

When treated with methylmagnesium iodide, it give tetramethyldiphosphine disulfide ([Me₂P(S)].₂.