Kinetics of dichlorocyclopropanation of vinylcyclohexane catalyzed by a new multi-site phase transfer catalyst

摘要

In this work, a novel soluble multi-site phase transfer catalyst viz., 1,4-bis-(ethylmethyleneammounium chloride)-2,5-dimethoxybenzene (BEMACDB) was synthesized and its catalytic efficiency was assessed by observing the kinetics of dichlorocarbene addition to vinylcyclohexane. The formation of the product was monitored by GLC. Dichlorocyclopropanation of vinylcyclohexane catalyzed by the new phase transfer catalyst was carried out in two-phase medium under pseudo-first-order conditions by keeping aqueous sodium hydroxide and chloroform in excess. This newly synthesized phase transfer catalyst possesses higher activity than the commercially available single-site phase transfer catalysts. The effect of various experimental parameters on the rate of the reaction has been studied. From the Arrhenius plot, the activation energy was found to be 16.07 kcal mol~(-1). Also thermodynamic parameters such as ΔS~#, ΔG~# and ΔH~# were evaluated; based on the experimental results, a suitable mechanism is proposed.