IN SEARCH OF THE SPIN-DELOCALIZATION EFFECT FROM THE CORRELATION-ANALYSIS OF RELATIVE RATES OF THE TRICHLOROMETHYL-BROMO-ADDITION REACTIONSTO 14 P-Y-SUBSTITUTED PHENYLACETYLENES

A rigorous procedure was applied to the measurement of the relative ra tes, i.e., k(r)(Y) = k(y)/k(H), Of trichloromethyl-bromo-addition reac tions to fourteen p-Y-substituted phenylacetylenes (I-Y, with Y = F, C l, Br, Me, t-Bu, OMe, SMe, SiMe(3), CF3, CN, NO2, SOMe, COMe and CO(2) Me). The reaction was run in cyclohexane under nitrogen atmosphere at 65+/-0.5 degrees C. All products were derived from the intermediate YC 6H4C=CHCCl3 adduct radicals. Correlation analysis of these rate data s eems to suggest that both a polar and a spin-delocalization effect are operating at the transition state.