Abstract
In continuation of previous work on aliphatic thiols, a quantitative comparison has been made of the relative reactivities of substituted thiophenols with respect to hydrogen abstraction by a free trivalent carbon radical.A competition method was employed involving reactions of 1‐cyano‐1‐cyclohexyl radicals with a mixture of two thiophenols in toluene solution at 110° C; 1‐cyano‐1‐cyclohexyl radicals were generated by thermal dissociation of 1,1′‐azo‐bis‐1‐cyclohexane nitrile. Relative reactivities were determined by measuring the residual amounts of thiophenols.In agreement with theoretical expectations the effects of the substituents appeared to be small, electron‐withdrawing groups decreasing the rate of the hydrogen abstraction reaction and electron‐repelling substituents increasing it; results were roughly in accordance with a Hammett ϱσ‐relationship, the value of ϱ amounting to about −0.4.