Effect of the polarity of the medium on the decomposition of cumyl hydroperoxide and cumene autoxidation in the presence of Cu(II)-acetylacetonate

Abstract

The effect of the polarity of the medium on the rate and the course of cumyl hydroperoxide (CHP) decomposition at 60 °C in the presence of copper acetylacetonate [Cu(acac) 2] as catalyst was investigated with the help of the radical-type inhibitor N-phenyl-2-naphthylamine (PNA). The influence on the oxidation rate of a mixture of cumene and nitrobenzene under analogous conditions was also studied. It was shown that the effect of Cu(acac) 2 on the decomposition of CHP is different from that of Co(acac) 2 catalyst investigated previously. Whereas Co(acac) 2 leads to the formation of free radicals only, a molecular course of the CHP decomposition was also observed in the presence of Cu(acac) 2. The values of the initial rates of the decomposition of CHP ( W in CHP) and of the consumption of PNA ( W in PNA) decrease with increase of the dielectric constant of the medium. However, the ratio between these rates remains independent of the change of the polarity of the medium. This fact shows that the dielectric constant does not affect the direction of the decomposition of CHP to molecular and to radical products.