Research On The Preparation Of High Value-added Chemicals From Chitin Biomass Catalyzed By Ionic Liquids

At present,the production of many industrial chemicals still relies on traditional petroleum resources.With the continuous consumption of fossil fuels,its continuous supply has become a thorny issue.In addition,the potential risks of environmental problems related to petroleum resources are high,so there is an urgent need to find renewable alternative resources for the production of industrial chemicals.Conversion of biomass into value-added platform chemicals has become an important research area,as a way to alleviate the resource crisis.Chitin biomass contains biologically fixed nitrogen,which can provide a nitrogen source for the synthesis of various N-containing chemicals.In this study,we degraded chitin biomass into 3-acetamido-5-acetylfuran(3A5AF).3A5AF is one of the most potential platform compounds,and many important nitrogen-containing chemicals can be synthesized from it.A series of pyridinium-based ionic liquids were synthesized and characterized by ¹H-NMR and FTIR spectroscopy.The pyridinium-based ionic liquids were used as a catalyst in the conversion of N-acetyl glucosamine(NAG,the monomer of chitin)to 3A5AF.Under normal pressure reflux conditions,1-carboxymethyl pyridinium chloride ionic liquid([CMPy]Cl)has the best catalytic effect,and the yield of 3A5AF reached 37.49%;On this basis,the co-catalyst B₂O₃ and Ca Cl₂ were added,and a series of reaction conditions were optimized.After reacting at 180°C for 20 min under oil bath conditions,the final yield of 3A5AF was increased to 67.37%,which is the highest yield of NAG converted to 3A5AF reported so far.In addition,HPLC-MS analysis has been utilized to elucidate the reaction mechanism.At the same time,a series of dipiperidine and bipyridine ionic liquids were designed and synthesized as catalysts,and they were also used in the conversion of NAG to 3A5AF.The reaction was carried out under atmospheric reflux conditions,and the types of ionic liquids,solvents,additives and reaction conditions were screened.Without any additives,4,4'-trimethylene-N,N'-carboxymethyl dipiperidinium chloride ionic liquid showed good catalytic effect,and the reaction was refluxed at 180°C under normal pressure for 20 min under oil bath conditions,the yield of 3A5AF was 42.81%.This research enriches the catalytic system of chitin biomass and provides new ideas for the research of chitin biomass.