Mechanism of Acid-Catalyzed Decomposition of Dicumyl Peroxide in Dodecane: Intermediacy of Cumene Hydroperoxide

Acid-catalyzed decomposition of dicumyl peroxide in dodecane from 60 to 130 degrees C produces alpha-methylstyrene and phenol as the major products. Pseudo-first-order rate constants were determined as a function of the temperature for the reaction of DCP with dodecylbenzenesulfonic acid in dodecane and resulted in an Arrhenius plot exhibiting two distinct kinetic regimes with differing activation energies: 76.9 kJ/mol at low temperatures (measured from 60 to 90 degrees C) and 8.50 kJ/mol at higher temperatures (measured from 90 to 130 degrees C). With employment of a combination of kinetics, product analysis, and trapping experiments, evidence is presented to show the intermediacy of cumene hydroperoxide a reactive intermediate absent from previous mechanistic descriptions of this process. The yield of cumene hydro peroxide production is discussed, and the mechanistic pathways for formation of the observed products are presented.