Additions of substituted phenylthiyl radicals to substituted α-methylstyrenes

The radical addition of substituted thiophenols to α-methylstyrene and substituted α-methylstyrenes has been investigated at 70°. Relative reactivities of pairs of thiophenols competing with individual alkenes can be utilized to obtain Hammett correlations. The interplay of substituent effects in alkene and thiyl radical leads to examples of non-linear rho values. Rationales for this behavior will be offered in terms of variable contributions from ground state and transition state electronic factors as well as in terms of possible mechanistic changes.