Energy data on the carbon‐carbon bond VI: Stability of ortho‐ethyl‐ and ortho‐isopropyl‐substituted diphenylmethyl radicals

The present investigation deals with the effect of the number of ortho ‐ethyl and ortho ‐isopropyl substituents on the stability of diarylmethyl radicals. These diarylmethyls were obtained by halogen abstraction from the correspondingly substituted benzhydryl chlorides. If not all ortho positions of the diarylmethyl carried ethyl or isopropyl groups, complete dimerization led to a symmetrical tetra‐arylethane; if all four positions were occupied by ethyl groups an equilibrium was reached between the radical and the dimer, while diarylmethyls with four ortho ‐isopropyl groups showed no dimerization at all. Radicals of the last type were prone to disproportionation, however.