(77d) Base-Catalyzed Reactions in Nh3-Enriched near-Critical Water

Near-critical water (NCW) has drawn increasing attention as an environmentally benign medium for organic chemical reactions, especially acid/base catalysis without added acid or base. However, problems such as slow reaction rate and poor selectivity exist for these organic syntheses in NCW, which greatly hinder the applications of the attractive technique in industrially interesting processes. We developed a novel solvent system to accelerate base-catalyzed reactions by the addition of NH3 to NCW. The reactions demonstrated include hydrolysis of cinnamaldehyde and aldol condensation of phenylaldehyde with acetaldehyde. The reaction kinetics of the two reactions were determined. The effects of the amounts of added NH3 and temperature on the reactions were also investigated. The results demonstrate the feasibility of using NH3-enriched NCW as an environmentally benign reaction medium for the acceleration of base-catalyzed reactions.