Method for preparing levulinic acid from chitin or chitosan directly by catalytic conversion

Abstract

The invention belongs to the technical fields of organic synthesis and chemical industry, and relates to a method for preparing levulinic acid from chitin or chitosan directly by catalytic conversion. The method comprises the following steps: evenly mixing and heating a reactant containing chitin or chitosan, an acidic ionic liquid and a solvent, and extracting the reaction solution to obtain the levulinic acid, wherein the yield exceeds 80%. The chitin or chitosan contained in shrimp and crab shells and various sources of biological wastes is directly subjected to one-step catalytic hydrolysis to obtain the platform chemical levulinic acid which is applicable to fine chemical engineering production; and thus, the invention provides a renewable resource utilization technique capable of changing wastes into valuable substances. In the catalytic hydrolysis process, the acidic ionic liquid is used instead of the sulfuric acid or any other highly-corrosive inorganic acid as the catalyst, and thus, conforms to the requirement of green chemistry, thereby avoiding the problems of device corrosion, difficulty in recovering acid liquor and the like. The ionic liquid catalyst can be completely recovered and recycled. The invention opens up a brand-new efficient, economic and environment-friendly way for utilizing waste shrimp and crab shells and other aquatic product wastes as well as seafood kitchen wastes.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis and chemical industry, and relates to a method for directly catalytically converting chitin or chitosan to prepare levulinic acid. Background technique [0002] Chitin, also known as chitin, chitin, chitin, and shell protein, is a polysaccharide biopolymer that widely exists in the shells of arthropods such as shrimps, crabs, and insects in nature, fungi, algae, and in plant cell walls. The annual biosynthesis of chitin in nature can reach 10 billion tons. It is the second largest biological resource after plant fiber on the earth, and it is an inexhaustible and renewable biological resource for human beings. [0003] The chemical name of chitin is [β-(1→4)-2-acetylamino-2-deoxy-D-glucose], and the molecular formula is (C 8 h 13 NO 5 ) n , acetylglucosamine monomers are connected by β(1→4) glycoside bonds, and the molecular weight is generally 10 6 above. The chemical structure of...

AI Technical Summary

Problems solved by technology

Although the chitin and chitosan products finally obtained by this treatment have higher added value, a large amount of waste acid and waste lye will be produced in the production process, and these waste liquids will cause huge pollution to the environment, and the treatment of these The waste liquid is not only technically difficult, but also very expensive, reaching more than 5 times the production cost of chitin

Moreover, water needs to be washed repeatedly in each production process, and at least about 400 tons of water will be consumed for every ton of chitin produced.

Images