Research On Self-Base Catalysis Of Organic Reactions In Near-Critical Water

The outstanding properties of near-critical water(NCW) comparing to that of water at ambient temperature and pressure are its high ionization constant and low dielectric constant,so it possesses self-acid/base catalysis function and special solubility of organics and inorganics. These unique properties indicate that NCW can act as a catalyst for organic reactions, also as a solvent and reactant. Acid and base catalyzed reactions can occur without the addition of acid and basic catalysts because of the function of NCW. NCW can also eliminate production of salts that result from the neutralization of acids used in conventional separations solving a significant environmental problem and instead of volatile organic solvents utilized heavily.In the preface and review of this paper, the profound applications of NCW in green chemical process and the research progress of organic reaction in domestic and abroad are introduced briefly. The review focuses on the reactions including the C-C bond formation and cleavage, rearrangement, hydration/dehydration, hydrolysis, oxidation/reduction, condensation, H-D exchange, decarboxylation.In order to investigate whether self-designed batch reactors can meet the demand of conducting organic reactions, a series of reactions of Claisen-Schmidt condensation reactions of benzaldehyde and acetone according to the published paper are conducted.Variations of temperature,time and reactant/H₂O ratio denpendence of conversion and yield for Claisen-Schmidt condensation reactions of benzaldehyde and acetone show no difference from the published paper as well as the optimum yield of benzylidene acetone, indicating the batch reactor systems can be pursued on related chemical reactions in near-critical water.Firstly, the reactivity of benzaldehyde is studied utilizing the autoclave designed by us in near-critical water. Stability datas of benzoic acid, benzyl alcohol and benzaldehyde are measured at temperature range from 240℃to 320℃. According to the analytical results, benzyl alcohol is more stable than benzoic acid in near-critical water and benzoic acid involves decarboxylation in high temperature conditions.The...