Method for hydrolyzing chitosan and chitin

Abstract

The invention relates to a method for hydrolyzing chitosan and chitin to prepare monosaccharide and oligosaccharide by using ionic liquid as a reaction medium and using protonic acid as a catalyst under the condition of heating. Particularly, the method comprises the following steps: dissolving the chitosan or the chitin into the ionic liquid, adding acid and water into the solution, and heating the solution to perform reaction so as to obtain a hydrolysis product of which the yield reaches up to 70 percent based on total reducing sugar. The method has the advantages of mild operation condition, high reaction speed, reusability of the ionic liquid, low cost, simple process, environmental friendliness and the like, provides a new method for efficiently degrading the chitosan and the chitin, and develops a new path for preparing general oceanic chemicals and medicinal health-care products in large scale.

Description

technical field [0001] The invention relates to the hydrolysis of chitosan and chitin, specifically a method for obtaining soluble monosaccharide and oligosaccharide by hydrolyzing chitosan and chitin with ionic liquid as solvent and acid as catalyst. Background technique [0002] Chitin is a natural polysaccharide composed of basic structural units N-acetyl-D-glucosamine connected by β-1,4-glycosidic bonds, and is widely found in the shells of arthropods (such as shrimps and crabs) and the cell walls of fungi. In nature, the annual biosynthesis of chitin reaches tens of billions of tons, second only to cellulose, and is an extremely rich renewable resource. Chitosan is a deacetylated product of chitin, containing D-glucosamine structural units, and is an alkaline polysaccharide. Chitin and chitosan are white or light yellow solids, insoluble in water, most organic solvents and dilute acids, but soluble in concentrated inorganic acids. [0003] Products such as D-glucosami...

AI Technical Summary

Problems solved by technology

Although concentrated acid hydrolysis can be realized at lower temperature and normal pressure, there are still a series of defects: concentrated acid corrodes equipment, troublesome post-treatment of hydrolyzate, high acid consumption, difficult recovery, etc.

Due to the mild reaction conditions and good selectivity of the oxidative degradation method, it has unique advantages in the preparation of oligosaccharides with specific molecular weights; however, this method destroys the amino groups during the degradation process, and the product quality is affected

Using hydrogen peroxide as an oxidizing agent can also degrade chitin and chitosan (Tanioka S, Matsui Y, Irie T, et al. Biosci. Biotechnol. Biochem., 1996, 60, 2001), but the reaction needs to be performed at a higher temperature and Low molecular weight products can only be obtained under the concentration of hydrogen peroxide, the process conditions are difficult to master, the reaction stability and repeatability are poor, and there are safety problems

[0006] In summary, there are obvious deficiencies in the degradation of chitin and chitosan in the prior art, such as low yield, poor repeatability, complex post-treatment, large amount of chemical reagents used, strong corrosion, and high cost

In addition, the molecular weight distribution of degradation products obtained by most prior art is too wide, and the monosaccharide yield is low