Bromination of 1,2-Dimethylenecyclohexane: Temperature Effect on Product Distribution

Abstract

In this study the electrophlic addition of bromine to an exocyclic diene, 1,2dimethylenecyclohexane, was investigated. The bromination of 1,2-dimethylenecyclohexaneyielded 1,2-bis(bromomethyl)cylohex-1-en at low temperature. Nevertheless, thebromination of 1,2-dimethylenecyclohexane at room temperature gave 1,4 addition product1,2-bis(bromomethyl)cylohex-1-en as a main product together with 1-bromo-1-(bromomethyl)-2-methylenecylohexane and 3-bromo-1,2-bis(bromomethyl)cyclohex-1-ene.Similarly, high temperature bromination of 1,2-bismethylenecyclohexane gave the radicalbromination products (3-bromo-1,2-bis(bromomethyl)cyclohex-1-ene and 3,6-dibromo-1,2-bis(bromomethyl)cyclohex-1-ene) in addition to the 1,4 addition product. While thebromination of exocylicdiene at room temperature with excess bromine gavetetrabrominated product 1,2-dibromo-1,2-bis(bromomethyl)cyclohexane as a sole product,the bromination of exocyclicdiene in high temperature with excess bromine resulted in atetra brominated product 1,2-dibromo-1,2-bis(bromomethyl)cyclohexane and the threebrominated product 3-bromo-1,2-bis(bromomethyl)cyclohex-1-ene together with theradicalic tetrabrominated product 3,6-dibromo-1,2-bis(bromomethyl)cyclohex-1-ene asmain products. However, the high temperature bromination of 1,4 brominated product withexcess bromine provided only the radicalic brominated product 3-bromo-1,2-bis(bromomethyl)cyclohex-1-ene and 3,6-dibromo-1,2-bis(bromomethyl)cyclohex-1-ene.Thus the functional agents which can be used as starting material in the synthesis ofmany compounds were synthesized, purified and characterized.