A Study On The Regularity Of Different Types Of Organic Synthesis Reactions By Supported Gold Nanocatalysts

Supported gold nanocatalysts have gained widespread interest and rapid development in organic synthesis due to their excellent activity,selectivity and stability.Exploring the influencing factors in different types of organic synthesis reactions and establishing model reactions to measure the catalytic activity of supported Au NPs is important for designing efficient nanogold catalytic systems.Nitrogen-containing organic compounds are important building blocks and intermediates.Hydroamination of C≡C or C=C with amines is the most cost-effective route to synthesize these compounds.In this thesis,we focus on the influencing factors and regularity of this reaction.Selective alcohols oxidation to aldehydes and nitroarenes reduction of azo/azoxy compounds are also important organic transformations that have triggered extensive studies.In order to explore the regularity of hydroamination reactions,these two types of reactions are simultaneously investigated for a comparative analysis in this work.The details of the study are as follows:Firstly,a series of supported gold nanocatalysts were prepared and characterized by a series of techniques such as XRD,UV-Vis,XPS and TEM.The effect of reaction temperatures,supports（TiO₂,ZrO₂,Al₂O₃,CeO₂）,catalyst calcination temperatures（250℃,450℃）,calcination atmospheres,Au loading,incorporation of a second metal（Ag,Cu,Pt,Pd）,metallic state of Au,gold leaching and other aspects on the activity of hydroamination reactions over supported Au NPs were investigated.The results showed that calcination at high temperature caused dramatic decrease of the activity for the hydroamination reaction,and the Au NPs on different support exhibited similar trend before and after the calcination process.These indicated that the catalyst performance was not depended on the types of support for hydroamination reaction.After excluding the influence of gold leaching and lysine addition in the catalyst preparation process,as well as combining UV-Vis,TEM characterization with experimental results,it could conclude that the hydroamination reaction depended on the particle size of supported Au NPs.The designed experiments further confirmed that the hydroamination reaction is very sensitive to the loaded Au NPs and depends only on the metallic state of Au.Furthermore,we must be very cautious if the average particle size is utilized for evaluating the activity of supported Au NPs in hydroamination reaction.The particle distribution should be within an extremely narrow range.Secondly,we investigated the alcohol oxidation reactions and nitroarenes reduction reactions.A series of catalysts were utilized and it was found that these two reactions were dependent on both supports and Au NPs.Our results may provide guidance for the design of efficient catalysts for gold hydroamination reactions and may establish a reaction model for the future evaluation of gold nanocatalytic systems under mild conditions.