On the induced decomposition of α-phenylethylhydroperoxide by peroxy radicals

Abstract

The induced decomposition of α-phenylethylhydroperoxide (HROOH) has been investigated in three different systems: hydroperoxide + cyclohexene + AIBN + O2 (I); cyclohexene substituted by isooctane (II), and cyclohexene substituted by chlorobenzene (III). The decomposition products of the HROOH were in all cases acetophenone (RO) and methylphenylcarbinol (HROH).It was established that peroxy radicals induced the decomposition. The considerable material balance deficit in I is due to the addition of the peroxy radicals to cyclohexene the rate constant of which was estimated from the experimental data. No material balance deficit was observed with II. Experiments supported the assumption that both RO and HROH were formed simultaneously in the interaction between peroxy radicals and HROOH.The rate constant of the reaction HRO2• + HROOH → HROH + O2 + HRO• was measured as k = 1.03 × 109 exp (−13 100/RT). It is suggested that in the autoxidation of ethylbenzene the induced decomposition of HROOH is fast enough to be the main source of RO and HROH.