Kinetic study of dichlorocyclopropanation under phase-transfer catalysis and assisted by microwave irradiation

• Kinetics of synthesizing 1,1-dichloro-2-hexyl-cyclopropane.
• Phase-transfer catalysis and microwave irradiation.
• Interfacial reaction.
• S-8 compound as effective catalyst.

This work studies dichlorocyclopropanation which was performed by reacting olefins with chloroform in an alkaline solution of NaOH/organic solvent two-phase medium using phase-transfer catalysis (PTC) and microwave irradiation. The conventional quaternary ammonium salts were used as phase-transfer catalyst. A new compound 3-(N,N-dimethyloctylammonio)-propansulfonate (S-8) which was synthesized from the reaction of dimethyloctyl-amine and 1,3-propansultone, was also employed as the phase-transfer catalyst. We found that the catalyst (S-8) is more effective than those of the conventional quaternary ammonium salts in dichlorocyclopropanation. The addition was preceded via the production of dichlorocarbene from the reaction of chloroform and NaOH. The advantage of using microwave irradiation is that it increases the reaction rate and the conversion. Based on the experimental data, a rational mechanism of the interfacial reaction is proposed. The reactions follow a pseudo-first-order rate law. A rate expression was developed to describe the kinetic behavior from which the apparent rate constant (kapp) of the organic-phase reaction was obtained. The kinetics of the reaction in studying the effects of reaction conditions on the conversion of reactant and the apparent rate constant (kapp) were investigated in detail. Rational explanations of the resulting phenomena are provided.