Study On The Catalytic Reaction Of Henry And The Mannich Reaction In Protease In Water

As a biocatalyst, enzyme has many advantages, for example, high efficiency,tenderness, high specificity. Enzymatic methods have been expanded rapidly for chemical synthesis. As research continues, people found that enzyme has catalytic promiscuity.Catalytic promiscuity of enzyme means enzyme can catalyze different organic reactions with its active-site. Nowadays, reports about catalytic promiscuity of enzyme are more and more popular, the study of enzymatic promiscuity has been a research hotspot of biological catalysis. Using water as the solvent of enzyme-catalyzed organic reactions has lots of potential advantages. For example, The water solubility of enzyme is higher than other mediums, water is cheap and easy to get, simple operation and the ease of product isolation, and environmentally friendly.In this thesis,hydrolase-catalyzed organic condensation reactions in the aqueous medium was mainly studied. The content is divided into four chapters.In the first chapter, the application of some enzymaticorganic synthesis and some organic reactions in the aqueous medium were introduced.In the second chapter, the Proteinase,from Aspergillus melleus(AMP) catalysis take the fragrant aldehydes and nitromethane as the substrate of the Henry reactions was studied,the influences of enzyme, solvent, enzyme loading, temperature, and mole ratio of substrateswere investigated. The three concrol experiments proved that the active site of the Proteinase,from Aspergillus melleus(AMP) for those enzymic reactions. We found that the optimized reaction conditions for the model reaction are as followed: water is used as solvent, the mole ratio of 4-nitrobenzaldehyde / nitromethane is 1:15, and the reaction temperature is 40℃. the Proteinase,from Aspergillus melleus(AMP) can catalyze the Henry reaction and the yield is up to 86.8%.In the third chapter, enzyme-catalyzed Mannich reaction was studied. The reaction conditions, including reaction enzyme source, solvents, temperature, enzyme loading, and the mole ratio of substrates were optimized. The concrol experiments proved that the active site of enzyme for those enzymic reactions. We found that when the reaction temprature is55℃,Papain, from papaya latex(PLP) has the highest catalytic abillity. The yield of this Mannich reaction between 4-nitrobenzaldehyde, aniline, and cyclohexanoneis up to 89.5%.This method as mild conditions, good adaptability to different substrates, avoiding the use of poisonous and volatile solvents, is upto the standard of green chemistry.In the fourth chapter, the optimized reaction conditions of Henry reaction and Mannich reaction were summarized, and the advantages of using enzyme catalytic promiscuity for the organic synthesis in the aqueous medium were illuminated.