ESR SPECTROSCOPIC INVESTIGATION OF STERIC AND POLAR FACTORS IN THE ADDITION OF RADICALS TO UNSATURATED-COMPOUNDS

The rate constants of the addition of CCl3CH2CClCH3(R6) radicals to alpha-methyl-styrene, styrene, methyl methacrylate, methyl acrylate, and acrylonitrile and of CCl3CH2C(CH3)2(R7) radicals to styrene, methyl acrylate, and acrylonitrile were determined by ESR spectroscopy. It was shown that the radicals R6 and R7 possess approximately equal reactivity in addition to unsaturated compounds, despite the difference in the donor-acceptor properties of the substituents at the vinyl group. In a comparison of the reactivity of radicals R6 and R7 with the reactivity of radicals CCl3CH2CH2(R1), CCl3CH2CHCH3(R3), CCl3CH2-CHCl(R4), and ClCH2CH2CCl2(R5) [1] in addition reactions, it was shown that polar and steric effects of the substituents situated in the alpha-position to the radical site of the above-mentioned radicals, as well as the donor-acceptor properties of the substituents at the vinyl group in the unsaturated compounds, lead to appreciable changes in reactivity.