Kinetic Study of Dichlorocyclopropanation of 1,7-Octadiene under Phase-Transfer Catalysis Conditions at High Alkaline Concentration

Abstract

The phase-transfer-catalyzed reaction of chloroform and 1,7-octadiene was carried out in an alkaline solution of a NaOH/chloroform two-phase medium. Dichlorocarbene, which is an active species to react with 1,7-octadiene in the organic phase, is generated from the reaction of chloroform, sodium hydroxide, and quaternary ammonium salt at the interface between the two phases. The reaction is dramatically enhanced by adding a small quantity of quaternary ammonium salt. An interfacial reaction mechanism was proposed to explain the characteristics of the reaction. A pseudo-first-order rate law is used to describe the reaction rate at high alkaline concentration (>50 wt %). Kinetics of the reaction including the effect of the reaction conditions on the conversion of 1,7-octadiene were investigated. A rational explanation was made for a peculiar phenomenon that the conversion of 1,7-octadiene (or the reaction rate) was increased and then decreased with an increase in the amount of sodium hydroxide and the amount of benzyltriethylammonium chloride catalyst.