RADICAL-ADDITION REACTION OF BENZENESELENOL TO STYRENE - KINETICS OF THE MODEL OF POLYADDITION

The addition reaction mechanism of benzeneselenol (BSe) to styrene (St) was studied as a model of the polyaddition of 1,4-benzenediselenol (BDSe) to 1,4-divinylbenzene (DVB). The addition reaction of BSe to St was carried out with AIBN initiator in benzene at 70-degrees-C under N2. The main product of anti-Markownikoff's structure (phiSeCH2CH2phi) was obtained in about 60% yield in 10 h reaction, but hardly increased after that. Then, side reactions were investigated in detail to account for such behavior, which was quite different from that of benzenethiol to St. This model addition reaction behavior was similar to that of polyaddition of BDSe to DVB. The kinetic study shows that the addition rate depends on the first order of [St], 0.5 order of [AIBN], and is independent of [BSe], and the rate-determining step is the addition reaction of benzeneseleno radical to St. On the basis of the results of modified Hammett plot considering a resonance effect, it is estimated that a perturbation between SOMO of benzeneseleno radical and HOMO of St is an important controlling factor for this reaction.