PROCESS FOR PRODUCING 1,1-DICHLORO-4-METHYL-1,3-PENTADIENE

摘要

A process is described for the preparation of 1,1-dichloro-4-methyl- 1,3-pentadiene in which 1,1,1,4- tetrachloro-2-hydroxy-4- methylpentane or an acylated derivative thereof is subjected to selective reductive elimination (e.g. with metal powder or by catalytic hydrogenation) to give 1,1,4-trichloro- 4-methyl-pent-1-ene. The latter is then dehydrochlorinated to give the pentadiene. The tetrachloro starting materials may be prepared by reaction of chloral and isobutylene to give a mixture of 1,1,1-trichloro-2-hydroxy-4-methyl- pent-3-ene and -4-ene; this mixture is then treated with HCl to give the tetrachloro-hydroxy-methylpentane, or treated with HCl and acylated (in either order to give the acylated derivatives.