The Esterolytic activity of poly(N-alkylimidazoles). The effect of ester chain length in the substrate and alkyl chain length in the catalyst on the esterolytic activity of poly(N-alkylimidazoles).

Abstract

In an effort to exploit the enhancement in catalytic activity which might be derived through hydrophobic interactions between polymeric catalyst and substrate, 1-methyl-5-vinylimidazole (l-Me-5-VIm), l-methyl-4-vinylimidazole (l-Me-4-VIm), 1-butyl-5-vinylimidazole (l-Bu-5-VIm), and 1-butyl-4-vinylimidazole (1-Bu-4-VIm) have been synthesized and polymerized. In 28.5% ethanol-water, poly( 1-alkyl-5-vinylimidazoles) proved to be efficient catalysts for the hydrolysis of various 3-nitro-4-acyloxybenzoic acids (Sn-, where n denotes the acyl chain length). Order of magnitude rate enhancements, as compared to the model compound, 1,5-dimethylimidazole (1,5-DMIm), were observed in the poly(l-alkyl-5-vinylimidazole)-catalyzed solvolysis of S12- and S18-. Poly(1-Me-5-VIm) catalyzes the hydrolysis of S18- 88 times faster than does 1,5-DMIm. The poly(l-Me-5-VIm) catalyzed hydrolysis of S18- in ethanol-water was analyzed in terms of a simple Michaelis-Menten type mechanism. Vmax and Km were determined to be 40.2 X 10-7 M min-1 and 2.20 X 10-5 M, respectively.