The Researches On Catalytic Chemoselective Hydrogenation Reaction In Novel Green Reaction Systems

Hydrogenation reaction is the fundamental reaction for chemical transformation, and it can simply increase the number of hydrogen atoms in organic compounds and make relatively unsaturated organic compounds into saturated organic compounds. Considering the importance of hydrogenation reaction, the development of clean, efficient green hydrogenation reaction system has far-reaching research significance.According to the perspective of green chemistry, we chose green reaction solvents and green catalysts for hydrogenation of the unsaturated aldehydes, ketones, olefins or nitrobenzene derivatives and the hydrogenation related reaction, such as hydrogen transfer reaction, and the redox esterification reaction of α,β-unsaturated aldehydes and alcohols which generated saturated ester. The main research contents have the following several aspects:In hydrogenation reaction by H2as hydrogen donor, the Ni nanoparticles were stabilized by the mixed micelle of the block copolymer P123/[BMMIM]OAc ionic liquids and employed for aqueous phase hydrogenation reaction. It could be demonstrated that the relationship of the preparation conditions and physical-chemical properties (size and surface charge properties of metal nanoparticles) with the performance of Ni catalyst through instrumental characterization and the activity tests of Ni catalysts. It was found that preparation conditions of Ni nanoparticles have great influence on the activity, such as the reduction temperature and the amount of stabilizers and so on. The synthesized Ni nanoparticles showed the excellent catalytic activity and selectivity for the selective hydrogenation of C=C and nitro compounds in the aqueous phase under very mild reaction conditions. And the Ni catalysts can be recycled at least for eight times without significant decrease in catalytic activity. The results of characterization revealed that the mixed micelles stabilized Ni NPs catalysts were highly dispersed in aqueous phase even after five times catalytic recycles. In addition, The addition of ionic liquid ([BMMIm]OAc) can afford the basicity and an additional steric protection from aggregation of Ni NPs, resulting in enhancing stability and catalytic activity of Ni NPs.Generally, it is necessary for adding alkaline substances to transfer hydrogenation reaction system if isopropanol as hydrogen donor. Hence, supported Au nanoparticles was synthesized and applied for transfer hydrogenation in isopropanol without alkaline. Through comparing the different preparation methods, supports and reduction condition, it was found that the calcined MgAl-hydrotalcite under550℃as the support, and supported Au nanoparticles was synthesized through urea deposition precipitation method and then reduced by NaBH4. It was found that the MgAl oxides was regenerated to the MgAl-hydrotalcite structure. The Au0was the active center for the transfer hydrogenation reaction. The Au nanoparticles could be applied for the transfer hydrogenation of aromatic aldehydes, ketones and nitrobenzene derivatives, and showed high catalytic activity and selectivity. Au catalysts could be recycled without significant decrease in catalytic activity.The internal redox esterification of α,β-unsaturated aldehydes and alcohols is usually catalyzed by deprotonation of azolium salts such as thiazolium, imidazolium, and triazolium salts in the presence of bases. In the part of redox esterification reaction, different ionic liquids were applied as catalysts and reaction solvents. It was found that the Lewis basic ionic liquid,1-butyl-3-methylimidazolium acetate ([BMIM]OAc), exhibited the highest activity for this reaction. The neutral and Br(?)nsted basic ionic liquids can not catalyze redox esterification and the base strength have strong effect on the yield of the saturated ester.