The Study Of Catalysis For Sulfide Oxidation And Allylic Alcohols Epoxidation Reaction Of Polyoxometalates

Polyoxometalates?POMs?,a novel catalyst with multiple functions,have attracted tremendous attention in recent years.It can be used either as an environment-friendly catalyst that is non-volatile,odorless,non-toxic,and easy to separate,or as a bifunctional catalyst that combines redox and acidity.In addition,the two characteristics,redox and acidity,can be regulated at the atomics or molecular level,making the application of polyoxometalates in the field of catalysis significant and far-reaching.Sulfide oxidation is the most important method for preparing sulfoxide and sulfone,which are the important synthetic intermediates in the fine chemical industry,and it is of great significance for deep desulfurization of oils.Epoxy alcohols,as the main product obtained from epoxidation of allylic alcohols,known as universal intermediates,contain reactive epoxy groups,which make them easy to react with hydroxyl,carboxyl,amine,and amide compounds containing active hydrogen atom,and a variety of new compounds can be formed by combining different ring-opening modes with functional groups.Hence,the study of sulfide oxidation reaction and allylic alcohols epoxidation reaction will have a negligible significance in industry and in life.The dissertation is divided into three chapters to systematic study sulfide oxidation reaction and allylic alcohols epoxidation reaction catalyzed by polyoxometalates with diverse compositions and structures.The cyclic performance of the catalysts and experiment conditions were also explored.The corresponding theoretical guidance would be provided for the design and synthesis of novel polyoxometalates by this paper.1This chapter mainly studies the oxidation of sulfides catalyzed by POMs.The catalysts include a pyrazinedicarboxylate-bridgingrare-earth-containingpolytungstoarsenateaggregate,a polyoxovanadate-based carboxylate derivative,a series of HEDP-based polytungstoarsenate clusters,a Ru-containing organic-inorganic hybrid polytungstoarsenate cluster and a novel class of organophosphonate-based polyoxomolybdates.The first two catalysts demonstrate better catalytic activity,whereas the cycle performance is slightly poor.The third catalyst showed a general catalytic activity.The latter two catalysts exhibit better catalytic activity and recycle performance.By comparison experiments,we speculate that the catalytic active site may be located on the W,Mo and V atoms in the skeleton of POMs.2This chapter mainly studies the epoxidation of allylic alcohols catalyzed by polytungstoarsenate aggregates.The catalysts include a citric acid-bridging Y-containing polytungstoarsenate aggregate and a glyphosate-based polytungstoarsenate clusters.The first one show relatively better catalytic activity on epoxidation of prenol and have a certain recycling performance;the latter one,as a homogeneous catalyst,exhibit particularly excellent catalytic activity.Based on experimental results,we speculate that the catalytically active center is located on the W atoms of POMs.3This chapter mainly studies the epoxidation of allylic alcohols catalyzed by PONb/POTa.The catalysts include the Lindqvist structure of[Nb₆O₁₉]^8-and[Ta₆O₁₉]^8-,a Ni-containing decaniobate incorporating organic ligands and a novel phosphorus incorporated peroxopolyoxoniobate.The last one has a general catalytic activity;the former three kinds of homogeneous catalysts exhibit particularly excellent catalytic activity.Based on experimental results,we speculate that the catalytically active center is located on the Nb/Ta atoms of POMs.