Ritter-type reactions catalyzed by high-silica MFI zeolites

Catalytic reaction of acrylonitrile (AN) with isopropyl alcohol (IPA) to N-isopropyl acrylamide has been studied using MFI zeolites in a solid-liquid reaction system. Turnover number (TON), which was defined as the number of the product molecule divided by the number of the acid site, increased as the Si/Al atomic ratio of MFI zeolites increased. It was deduced that both the hydrophobicity and acid strength of the zeolites were plausible factors in determining the specific activity. Secondary alcohols such as 2-butanol, 3-pentanol, and cyclohexanol as well as IPA showed reactivities in the reaction with AN, while primary alcohols like 1-butanol and isobutyl alcohol gave little products. Tert-butyl alcohol was readily dehydrated to isobutylene and the yield of N-tert-butyl acrylamide was thus low. The reaction of AN with 1-adamantanol was very slow over the MFI zeolites due to the limitation of adsorption in the restricted pores. While MFI zeolites were deactivated due to the blockage of the micropores by the polyacrylonitrile formed during the reaction, the catalytic activity was mostly recovered by calcination at 773 K in air. (C) 2001 Elsevier Science B.V. All rights reserved.