Silver Based Covalent Organic Polymer Catalytic CO₂ Convert To Cyclic Compounds

Recent years has witnessed serious environment problems caused by increasing carbon dioxide（CO₂）concentration,thus how to protect it from becoming more worse is an urgent question.CO₂is a kind of cheap,abundant and renewable C1 resource,which can be converted into important fine chemicals,such as cyclic carbonate,2-oxazolidinone,cyclic carbonate etc.^[1-6]However,due to its thermodynamic stability and chemical inert nature,CO₂activation usually requires some harsh conditions such as high temperature and high pressure.Hence,it is very necessary to develop a mild,green and efficient catalytic system.Based on this,we have designed and prepared a series of porous organic polymer supported silver nanocatalysts,which were applied into the cyclocarbonylation reaction of CO₂under mild conditions.Firstly,we have prepared covalent organic polymer Tp MDA from trichlorohydrin and4,4’-diaminodiphenyl methane.which was used as carrier to support Ag nanoaparticles by chemical reduction method,thereby obtaining Ag/Tp MDA catalyst.Afterwards,the obtained catalyst was applied into the reaction of CO₂with proparynylamine to form 2-oxazolidinone.The catalyst shows excellent catalytic activity and stability.A series of characterizations suggested that the abundant pore structure and surface functional groups of Tp MDA can limit the mean particle size of Ag nanoparticles in only 2.8 nm,and anchor and disperse the active species to improve its stability.As a consequence,it can efficiently trigger the reaction of propargylamine with CO₂into numerous oxazolidinones under mild conditions.Furthermore,CO₂physical adsorption and Raman reflection were carried out to investigate the possible mechanism,and thus a synergistic catalysis of Ag/Tp MDA for CO₂adsorption and activation was proposed.Secondly,a Tp Tt material was synthesized by Schiff condensation using trialdehyde resorcinol and melamine as monomers,which can efficiently adsorb CO₂molecule and anchor Ag nanoparticles because of its abundant N atoms.Ag/Tp Tt catalyst was prepared was using Tp Tt as carrier through in situ reduction method,which was then applied into prompting the cyclocarbonylation of CO₂and propargyl alcohols and efficiently acquired a series of cyclic carbonates under mild conditions.By means of CO₂physical adsorption and¹H NMR analysis,a synergistic catalytic mechanism of CO₂adsorption and activation was proposed.Finally,a covalent triazine framework（CTP-TPT）was prepared from melamine and2,4,6-tris（4-aldehyde phenoxy）-1,3,5-triazine by Schiff base reaction,which was then served as supporter to fabricated Ag/CTP-TPT catalyst by chemical reduction method.Also,the obtained Ag/CTP-TPT catalyst was applied into the synthesis of oxazolidinone through the three-component cyclocarbonylation of propargyl alcohol and primary amine with CO₂,and showcased excellent catalytic performance.A series of characterization techniques suggested abundant porous structures and surface groups in the material,which might greatly promote the dispersion and stability of Ag nanoparticles.These features endow is excellent catalytic performance towards the carboxylation reaction of terminal alkynyl alcohol and primary amine with CO₂.