THE NON-AQUEOUS MICELLAR CATALYSIS OF THE DECOMPOSITION OF BENZYL CHLOROFORMATE

Abstract

The decomposition of benzyl chloroformate in decane was chosen as a model reaction for the study of micellar catalysis in non-polar solvents. The surfactants chosen as the catalysts were the sodium, zinc, chromium, aluminum, and cerium (III) salts of di-(2-ethyl-hexyl) succinate sulfonic acid. The reaction was strongly catalyzed (in one case more than 5000 times) by the micelles. The plots of the rate constants versus the catalyst concentrations showed critical micelle concentrations and the characteristics of saturation kinetics which confirmed that the catalysis was micellar. The catalytic effectiveness of the different salts was not directly related to their Hammett acidities. The zinc salt which was third most acidic salt was the most powerful catalyst. The activation enthalpies of several of the catalyzed reactions were unusually large (Zn(II), ΔH ≠ = 266 kilo joules/mole; Al(III), δH ≠ = 147 kilojoules/mole). These results were interpreted as showing the effects of micellar geometry on the effectivenesses of the catalysts.