The uncatalyzed, gas phase pyrolysis of 1-bromomethyl-2-methyltetrafluoro-I-cyclobutene at 630" in a fastflowing nitrogen stream gives a mixture of 1, 2- dimethylenetetrafluorocyclobutane (19%), l, l-difluoro-2-methyl-ene-3- difluoromethylenecyclobutane (25%), and 1, 2-dimethyltetrafluoro-l-cyclobutene (5%). Physical and chemical properties of the two dienes are in accord with the structures given. ...
