Organohalogen compounds. Part I. The preparation of 1,4-dibromo-2,3-dimethylbuta-1,3-diene and 1-bromo-4-chloro-2,3-dimethylbuta-1,3-diene

Abstract

Dehydrobromination of 1,2,3,4-tetrabromo-2,3-dimethylbutane gives 1,4-dibromo-2,3-dimethylbuta-1,3-diene in high yield, but 3,4-dibromo-2,3-dimethylbut-1-ene does not dehydrobrominate to 1-bromo-2,3-dimethylbuta-1,3-diene. Chlorination of trans-1,4-dibromo-2,3-dimethylbut-2-ene gives a mixture of 1,3-dibromo-2,4-di-chloro-2,3-dimethylbutane and a substitution product probably 4-bromo-3-chloro-2-chloromethyl-3-methylbut-1-ene; the former dehydrohalogenates to give either 4-bromo-1,3-dichloro-2,3-dimethylbut-1-ene or 1-bromo-4-chloro-2,3-dimethylbuta-1,3-diene depending on the reaction conditions.