KINETIC STUDY OF THE SYNTHESIS OF DICHLOROCYCLOPROPANE BY TRIALKYLAMMONIUM PROPANSULTANS AS NEW PHASE-TRANSFER CATALYSTS

Abstract

In this work, the synthesis of dichlorocyclopropane, from a phase-transfer catalyzed reaction of chloroform and olefins (1-octene or 1,7-octadiene), was carried out in an alkaline solution of NaOH/chloroform two-phase medium. Trialkylammonium propansultan, a zwitterionic compound, acts as a new phase-transfer catalyst of high reactivity to produce high yields of dichlorocyclopropane. Dichlorocarbene (:CCl₂), which is an active species to react with olefins to produce dichlorocyclopropane in the organic phase, is generated from the reaction of chloroform, sodium hydroxide, and trialkylammonium propansultan as phase-transfer catalyst at the interface between two phases. The dichlorocyclopropanation is dramatically enhanced by adding a small quantity of trialkylammonium propansultan. An interfacial reaction mechanism was proposed to explain the reaction characteristics. A pseudo first-order rate law is used to describe the reaction rate at high alkaline concentration solution (>50 wt% NaOH). There is detailed investigation of the reaction kinetics, including the effect of the reaction conditions—the agitation speed, temperature, phase-transfer catalysts and their amounts, the amount of chloroform, the amount of 1-octene, inorganic salt (NaCl and Na₂SO₃), and alkali concentration—on the conversion of 1-octene.

Keywords:

• Dichlorocyclopropanation
• Phase-transfer catalysis
• 1-Octene
• Trialkylammonium propansultan
• chloroform

Acknowledgment

The authors would like to thank the National Science Council for financial support under grant NSC-90-2214-E-029-007.

Notes

100% conversion was achieved at 30 min. The reaction conditions for all runs were 8 g of NaOH, 0.5 mmol of catalyst, 12 mL of water, 0.02 mol of organic phase ractant, 20 mL of chloroform, 40 min of reaction, 800 rpm.

^a 4-(Dimethyloctylammonium) propansultan.

^b 4-(Dimethyltetradecylammonium) propansultan.

^c Benzyltriethylammonium chloride.