3-Methylene-l, 4-~ yclohexadiene, 1, 5-methylene-1, 3-cyclohexadiene, 2, l-methylene-1, 4- dihydronaphthalene, 5, and 9-methylene-9, 10-dihydroanthracene, 8, react with second- order kinetics in benzene solution. The activation parameters for the reaction of 1, 5, and 8, especially the frequency factor, suggest a nonconcerted reaction with little orientational demand in the transition state. The frequency factor for the reaction of 2 suggests a ...
