Oxidation of basic zinc dibutyl dithiophosphate by cumyl hydroperoxide at 25 °C; kinetic studies by h.p.l.c.

Abstract

Over an 11 h reaction period in cyclohexane at 25 °C, [(BuO)₂PS₂]₆Zn₄O (0.01 mol dm^–3) induces solely the homolytic decomposition of 0.12 mol dm^–3 cumyl hydroperoxide. Cumyloxy radicals may abstract hydrogen atoms to form the major aromatic product cumyl alcohol; they may combine to produce dcumyl peroxide; or they may be scavenged by a Zn(SPS) unit which reduces the cumyloxy radicals to 2-phenylpropene. The formation of this last species by the reduction of cumyloxy radicals occurs in contrast with the mechanism usually proposed, viz., by acid-catalysed dehydration of cumyl alcohol. Organothiophosphate oxidation products of [(BuO)₂PS₂]₆Zn₄O include [(BuO)₂PS₂]₂, [(BuO)₂PS₂]₂S, [(BuO)₂PS]₂S, and a monothiophosphate provisionally characterised as [(BuO)₂P(S)O]₂Zn.