Synthesis Of Cellulose-supported Catalysts And Their Applications In C-C Coupling Reactions

Cellulose is one of the most abundant natural polymers on earth. Due to its multiplehydroxyl groups in its backbone, more and more cellulose-supported catalysts weredeveloped by chemical modification of the hydroxyl groups. The exploitation ofcellulose-supported catalysts can meet the requirements of green chemistry andsustainable development strategy due to its high catalytic efficiency, easy separationfrom products and cheap raw materials; therefore，they have been widely used inorganic reactions.In this paper, cellulose tosylate (Cell-OTs) was first synthesized in DMAc/LiCl.Then OTs as a leaving group, different functional ligands were grafted onto cellulosebackbone using group transformation, then coordinated with palladium to preparecellulose-Pd complexes. In the first part, cellulose-supported triphenylphosphine wassynthesized through the nucleophilic substitution reaction of cellulose tosylate and4-hydroxyphenydiphenylphosphine, then coordinated with Pd(OAc)2in DMF to getthe catalyst. Its catalytic activity on Heck coupling reaction was evaluated. The effectsof different factors on Heck reaction were investigated, and the optimum conditionswere obtained. For most of substrates employed, the complex showed efficientcatalytic activity.Phosphine ligand is sensitive to air and moisture. Compared tophosphorus-containing ligands, NHCs tend to bind more strongly to metal centers. Soin the second part, catalyst precursor was prepared by the reaction of cellulosetosylate and N-methylimidazole, then the precursor coorinated with Pd(OAc)2inDMF to prepare the catalyst. Its catalytic activity on Suzuki coupling reaction wasevaluated. The effects of different conditions on yield were studied, the optimumconditions were obtained. Results showed that the complex can efficiently catalyzethe Suzuki reaction. Recycling use of catalyst results demonstrated the catalyst hadgood performance in the previous3cycles.