Osamu Kikuchi1, Keizô Suzuki1, Katsumi Tokumaru1
1Institute of Chemistry, The University of Tsukuba
Tóm tắt
Abstract
Radical-induced decomposition reactions of diacyl peroxides were investigated on the basis of the electronic structure of the peroxide-radical systems which were calculated using an approximate restricted open-shell SCF MO method in the MINDO/3 approximation, and on the basis of configuration analysis of the transition state of the reaction. For the transition state, (1) the change in peroxy O–O bond length is expected to be small, (2) the odd-electron density on the leaving group of the SH2 displacement is expected to be very small, although appreciable odd-electron delocalization from the radical to the peroxide was observed, (3) the charge-transfer (CT) interactions which correspond to electron transfer from the radical to the peroxide was found to be important in the transition state. The trends observed in the orbital energies of the LUMO of substituted dibenzoyl peroxides and in the CT character of the transition state, which involves the singly-occupied MO of the radical and the 2pσ* MO of the peroxide, agree well with the experimental facts, and strongly support a previous postulate that an important role is played by the 2pσ* MO of the peroxy O–O group in the reaction.
