Study On Knoevenagel Condensation Catalyzed By 3-aminopropyl-triethoxysilane Grafted On Graphene Oxide And Hydrosilylation Reaction Catalyzed By Platinum Based Catalysts

In this study,we firstly investigated the organic base grafted graphene oxide and its applications in the Knoevenagel condensation reaction.The Knoevenagel condensation reaction is an important reaction for the formation of a C=C bond between carbonyl and active methylene compounds,which has been widely used to synthesize intermediates of fine chemicals.It is well known that the Knoevenagel condensation is a base catalytic reaction.Thus,covalent functionalization of graphene oxide(GO)with an organic base 3-Aminopropyl-triethoxysilane(APTS)afforded a solid base catalyst,which was characterized by elemental analyses,XRD,TGA,FT-IR,XPS.The catalyst was applied in the Knoevenagel condensation reaction.The results reveal that the catalyst exhibits a highly efficiency for the condensation reaction,which gives over 90%yields for the condensation products.Compared with the catalysts utilized the common silica supports for grafting APTS(SiO2-APTS and MCM-41-APTS),the GO-APTS demonstrates a higher activity.Moreover,the catalyst can be easily separated from the reaction system and shows an excellent reusability(up to seven times).Secondly,the hydrosilylation reaction catalyzed by platinum based catalysts was studied.The hydrosilylation reaction is a reaction of Si-C bond formation,which is very important for the synthesis of organofunctional silanes.Herein,three kinds of platinum based catalysts were synthzied and their hydrosilylation acticivities were examinzed.(a)carboxylic acid-modified Speier's catalysts:the carboxylic acids with different acid strength and steric were added to the Speier's catalyst.The influence of the acid strength and steric on the hydrosilylation of styrene were investigated and a reasonable mechanism was proposed with the help of DFT calculation.The results revealed that the catalytic activity of hydrosilylation reaction is related to the acid strength of carboxylic acid,while the selectivity to ?-adduct is related to the steric of carboxylic acid.(b)ZD-Karstedt catalysts:a series of ZD-Karstedt catalysts were synthesized and their applications in preparing silicone were investigated.The results demonstrate that ZD-Karstedt catalysts exhibit high catalytic activities,but the activities are still lower than that of spl-5and spl-5B purchased from the market.Additionally,a low platinum yield is obtained in the synthesis of ZD-Karstedt.(c)BTL-Karstedt catalysts:BTL-Karstedt catalysts were synthesized and applied to synthesize silicone.The results show that BTL-Karstedt catalysts displayed a high catalytic activity which is compared to that of Clp-201 purchased from market.In addition,the BTL-Karstedt catalysts possess a good stability,facilitating the store of these catalysts.