Reaction of methylene with cyclobutene. Part 1

Abstract

The photolysis of diazomethane in the presence of cyclobutene has been investigated at various total pressures. Part 1 describes the reaction up to 2 atm, the vapour pressure of cyclobutene at room temperature. The experimental results can only be interpreted if the photolysis of diazomethane yields both singlet and triplet species of methylene. The initial products of the reaction of singlet methylene are bicyclo[2,1,0] pentane, 3-methylcyclobutene and 1-methylcyclobutene. These are all formed with high vibrational energy content and can undergo subsequent unimolecular isomerizations. A theoretical treatment of the isomerization of both 1- and 3-methylcyclobutenes is presented. The major product of the reaction involving triplet methylene is vinylcyclopropane.