Enzymatic Synthesis Isosorbide Ester

Plasticizers are additives in plastics that reduce the glass transition temperature of plastics and make them soft.Plastic products containing plasticizers can exhibit improved flexibility and durability.In recent years,due to scandals caused by the leakage of plasticizers,long-term use will cause leakage of o-phenyl-based plasticizers from materials,polluting the environment,and even contaminating foods pose a hidden danger to human health.Therefore,the production of environment-friendly bio-based plasticizers is a must.Isosorbide is a glycol derived from the intramolecular dehydration of sorbitol and is a white,crystalline,highly hydrophilic solid.Isosorbide is a bicyclic compound consisting of a diol and an oxygen-containing heterocycle containing two fused furan rings.The alcohol has two spatially different hydroxyl groups,resulting in different chemical reactivity.Because they are rigid molecules and have chirality and non-toxic characteristics,they are widely used as a new type of bio-based material in the fields of food,medicine,cosmetics,plastics,and polymers.The isosorbide diester synthesized by the reaction of isosorbide and fatty acid is directly added as a plasticizer in plastics,and does not need to be compounded with other plasticizers.The use of lipase as a catalyst is relatively small compared to chemically catalyzed by-products,no waste water is produced,there is little impact on the environment,the product purity is high,and the process is simple.Therefore,this paper will use lipase-catalyzed reaction of fatty acid and isosorbide to synthesize isosorbide diester.1?Synthesis reaction using oleic acid and isosorbide,through different acyl donors,different sources of lipase(Novo-435,RM IM and Ylip2 immobilized lipase),multi-enzyme catalysis,and using reaction tank to control water activity these factors to obtain the best reaction conditions to obtain a high content of isosorbide diester.After optimization,the optimal conditions for the catalysis were finally obtained,which was catalyzed by the immobilized Ylip2 lipase in the first 24 hours,the reaction temperature was 50 ? and was catalyzed by Novo-435 lipase after 24 hours,and the reaction temperature was 60 ?.After 48 hours,isosorbide was completely reacted.Since the acid was excessive,the relative content of oleic acid in the reaction system was 16.04%,the relative content of the monoester was 14.57%,and the relative amount of the diester was 69.4%.2?Based on the requirements of cost saving,energy saving and environmental protection,according to the mature method of immobilization with inorganic carrier diatomite in the laboratory,CALB fermentation broth was immobilized as a catalyst for the synthesis of isosorbide diester.Four kinds of ratios of immobilized lipase were selected to conduct the esterification assay and compared with Novo-435 and Ylip2 immobilized lipase.The appropriate multi-enzyme combination was selected for use in the experiment.The obtained product was refined,the acid number of the finally obtained isosorbide diester was 1.13,the yield was 80.14%,the relative content of the isosorbide diester in the product was 94.99%,and the relative content of the monoester was 4.75%.3?The thermal and mechanical properties of the refined isosorbide diester and PVC were tested,and compared with commercial mature plasticizers(DOP,DOA,ATBC,TOTM).Three ratios are selected during the blending process for optimization.The isosorbide diester was found to have excellent properties in comparison with the overall performance,similar to the properties of commercially available plasticizers,and some of the properties were even better.