Studies On Catalytic Performances Of Chitosan Palladium Complexs In Suzuki Coulping Reaction In Aqueous Phase

In this thesis，the recent progress about the palladium catalysts of Suzuki couplingreaction and catalysis applied research of chitosan-palladium complexes and the Green Suzukicoupling reaction especially the progress in aqueous phase was reviewed in detail. On thebasis, CS–PdCl2and Fe3O4–CS–PdCl2and FCS–PdCl2were prepared, and their catalyticperformances in the Suzuki coupling reaction in the0.1moL/L CTAB system through themethods of the single factor and orthogonal test were studied. The results are as follows.The catalytic properties of CS–PdCl₂on the reaction of bromo-anisole withphenylboronic acid were studied and obtained the optimal conditions:1mmol PhB（OH）₂,n（PhBr）: n（PhB（OH）2） as1.2:1, n（K₂CO₃）: n（PhB（OH）2） as2.5:1,0.03g catalyst（thecontent of palladium is1.83%）,85℃reacted for6hours. Underthe optimal conditions, theyield of4-methoxy-biphenyl could reach83.70%. The catalytic activity decreasedsignificantly after reused three times.The catalytic properties of Fe3O4–CS–PdCl₂on the reaction of bromobenzene withphenylboronic acid were studied and obtained the optimal conditions:1mmol PhB（OH）2,n（PhBr）: n（PhB（OH）2） as1.5:1, n（K₂CO₃）: n（PhB（OH）2） as3:1,0.03g catalyst（thecontent of palladium is1.78%）,70℃reacted for6hours. Under the optimal conditions, theyield of biphenyl could reach85.90%. The catalyst could be reused three times with thesatisfactory catalytic activity.The catalytic properties of FCS–PdCl₂complex on the reaction of bromobenzene withphenylboronic acid were studied and obtained the optimal conditions:1mmol PhB（OH）2,n（PhBr）: n（PhB（OH）2） as1.6:1, n（K2CO3）: n（PhB（OH）₂） as3:1,0.03g catalyst（thecontent of palladium is2.1%）,90℃reacted for2hours. Under the optimal conditions, theyield of biphenyl could reach84.69%. The catalyst could be reused three times with thesatisfactory catalytic activity.Comparing the catalytic performances of CS–PdCl₂and Fe3O₄–CS–PdCl2and FCS–PdCl₂on the reaction of iodobenzene and substituted bromobenzene and chlorobenzene withphenylboronic acid, we found that the catalytic activity of the electron–poor groups wasbetter than the electron-rich groups; the catalytic activity of the iodobenzene withphenylboronic acid was very high; however, the reaction of chlorobenzene withphenylboronic acid was very difficult, no satisfactory results were obtained even if longer reaction time and higher reaction temperature.The supported catalyst （Fe₃O₄–CS–PdCl₂） and chemical modification catalyst （FCS–PdCl₂） have higher stability and catalytic activity and reusability than the CS–PdCl₂. Naturalpolymer chitosan supported palladium complexes could economically and effectively catalyzethe Suzuki coupling reaction of iodobenzene and bromobenzene under mild conditions. TheSuzuki coupling reaction, it not only has vast potential in the scientific researching; but alsohas great development prospects in the industrial production. The more moderate and moreeconomical and more environmental stewardship and industrialization Suzuki couplingreaction has been explored constantly.