![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
A kinetic study of the solvolysis of six alkylphenyl thiophenoxyphosphonium chlorides in 50% water/methanol is reported. The rates of solvolysis, where thiophenol and phosphine oxides are formed, are little influenced by the substituents linked to phosphorus. The present findings are in sharp contrast to the 104 higher rate of the alkaline decomposition of tetraphenyl as compared to tialkylphenyl phosphonium salts, where phenyl is the leaving group. Further, the rate of solvolysis of the cyclic phenyl thiophenoxyphospholanium salt, is nearly identical to the rate of the corresponding dialkylphenyl thiophenoxyphosphonium compound. Calculation of the activation parameters of the solvolysis of thiophenoxyphosphonium compounds shows that the underlying reaction forces, expressed as activation energies and entropies, are strongly influenced by the substituents. The results suggest that the thiophenoxy group is expelled from the pentacovalent, trigonal bipyramidal reaction intermediate, before pseudorotation of the substituents linked to phosphorus takes place.