Kinetic study of the homogeneous methanolysis of tetraphosphorus decasulphide

Abstract

The rate of the homogeneous methanolysis of pure P₄S₁₀, dissolved in CS₂, has been measured at 0, 15, 25, and 35 °C for various MeOH:P₄S₁₀ molar ratios. The sole product detected was (MeO)₂PS₂H. At not too low concentrations, the reaction is virtually first order in [P₄S₁₀] and second order in [MeOH], owing probably to an autocatalytic process. The multistep reaction is kinetically controlled by the initial attack on P₄S₁₀; this is tentatively explained by the rigidity and geometry of the P₄S₁₀ cage molecule and/or by the spontaneous formation of reactive dithioxophosphoranes ZP(S)₂[Z = MeO– or > P(S)S–] from all alcoholysis intermediates. Calculated activation parameters are discussed. Novel data on the solubility of P₄S₁₀ are reported.