Free radical reactions in solution. Part 9. Further σ˙ values from decomposition of substituted dibenzylmercurials

Abstract

Di-para-substituted dibenzylmercurials (p-XC₆H₄CH₂)₂Hg (X = Br, CN, or SCH₃) have been prepared. From the rates of decomposition in octane at 140.2°, σ· values for the stabilizing influence of p-Br, p-CN, and p-SCH₃ have been evaluated as 0.20, 0.41, and 0.49, respectively. Comparison of the rates of decomposition of dibenzylmercury, p-methoxydibenzylmercury, and bis-(p-methoxybenzyl)mercury supports a mechanistic scheme involving homolysis of one C–Hg bond in the transition state, rather than simultaneous cleavage of both C–Hg bonds.