Isomerization of 1, 4-and 1, 2-Dichlorocyclohexanes by Antimony(V) Chloride

Abstract

Reactions of trans-1, 2-, cis-1, 2-, trans-1, 4-, and cis-1, 4-dichlorocyclohexanes with antimony (V) chloride were investigated. Although the isomerization of cis-l, 2-dichloride does not occur and a decrease of this compound happens (Fig. 2), the isomerization of other three dichlorides occurs. The yield of isomerized products of cis-and trans-1, 4-dichIorides are greater than that of trans-1, 2-dichloride. These different behaviors of the dichlorides were discussed in terms of their conformations. The distributions of cis-, trans-1, 3-, and-1, 4-dichlorides in the isomerized products occur irrespective of the starting dichloride or the reaction time (Table 1). Effects of solvent and temperature on these distributions were investigated. Mechanisms of the isomerization were discussed and it was suggested that carbonium ions, whose counter anion being hexachloroantimonate ion, should be the intermediates of the isomerization. The distributions of the products obtained by the isomerization were compared with those obtained by the isomerization due to the chlorination of cyclohexene with antimony(V) chloride. © 1977, The Chemical Society of Japan. All rights reserved.