Molecular Rearrangement in the Mercury-Photosensitized Reaction of Butene-1

Abstract

Mercury‐photosensitized reaction of butene‐1 has been studied at room temperature in the pressure range of 14 to 230 mm. Methyl cyclopropane is found to be formed by molecular rearrangement and its yield goes through a maximum at a pressure of about 65 mm. The dependence of the yield of this product on pressure is explained by postulating participation in the process of two excited states of equal lifetimes. These are, perhaps, the vibrationally excited triplets of butene‐1 and of methyl cyclopropane, the latter being formed from the former by an internal 1,2‐ or approximately 1,4‐ migration of an H atom. Molecular rearrangement to butene‐2 does not occur.