Method for synthesizing allantoin

Abstract

The invention relates to a method for synthesizing allantoin. The allantoin is synthesized by taking acid ionic liquid as a catalyst and glyoxylic acid and urea as raw materials. A process is simple, raw materials are bulk chemical raw materials, yield is high, the method is easy to industrially popularize, the yield of allantoin is stable and can reach over 68 percent, and the acid ionic liquid used as the catalyst can be repeatedly used for more than 5 times; and the process is pollution-free and environment-friendly, and has a good ecological effect and social and economic benefits. Through assay determination, the content of the obtained allantoin product is in the range required by the United States Pharmacopeia (USP29), and other indexes of the obtained allantoin product also meet the USP 29.

Description

technical field [0001] The invention relates to a method for synthesizing allantoin. Background technique [0002] Allantoin (allantoin), the chemical name is 1-ureidodiaziridine-2,4-dione, which belongs to imidazole heterocyclic compound, usually exists in the form of white crystal or crystalline powder, odorless and tasteless . [0003] Allantoin widely exists in nature, such as allantoic fluid, fetal urine, human and mammalian embryos and excreta, and tobacco, wheat grains, and sugar beets also contain allantoin. However, the amount of natural allantoin is limited, the extraction process is complicated, and the yield is extremely low, so most of the current commercial allantoin is artificially synthesized. [0004] In medicine, allantoin is a drug with multiple functions. It can be used directly or as an additive. Allantoin can treat various skin diseases, such as psoriasis, dermatitis, dry skin, etc., and can promote skin Cell and tissue growth, rapid wound healing an...

AI Technical Summary

Problems solved by technology

Li Guiyun and Ma Jiangquan disclosed in "Synthesis and Characterization of Allantoin" ("Journal of Jiangsu Institute of Petrochemical Technology") that the yield of allantoin was 59.3% with nitric acid and sulfuric acid mixed acid as catalyst, and its raw material glyoxylic acid was made of Produced by nitric acid oxidation method, allantoin is directly produced without purification, and the product will be affected by residual glyoxal, by-product oxalic acid and by-products of various reactions, and the quality will decrease

Lei Hong et al. disclosed the synthesis of allantoin by using inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid as catalysts in the "Summary of Allantoin Production Process and Market" ("Proceedings of the 21st Technical Exchange Conference of the National Medium Nitrogen Information Collaboration Group"). The yield is between 52% and 58%; Chinese Patent Publication No. CN1528749A, published on September 15, 2004, the name of the invention is "New Technology for Allantoin Synthesis", and the application discloses the use of metal catalysts to catalyze the synthesis of Allantoin yield can only reach 56%

In addition, there are many reports on the synthesis of allantoin with solid acid as a catalyst, but the yield is mostly below 60%. Only Shi Gaofeng et al. Heteropoly acid [H 3 PW 12 o 40 · x H 2 O] as a catalyst, the yield can reach 68.6%, but the amount of urea is too much; Fu Xinling et al. in 2007 "SO 4 2- / TiO 2 Synthesis of Allantoin Catalyzed by Solid Superacids" ("The 11th Academic Conference on Catalysis") 4 2- / TiO 2 The highest yield of allantoin catalyzed by solid superacid is only 57.35%, and the production of solid acid is difficult and costly, so it is not suitable for industrial production

In addition, the Chinese Patent Publication No. CN1765888A, published on May 3, 2006, is an invention titled "A Synthetic Process for Allantoin". Strongly acidic cation exchange resin can be used to catalyze the synthesis of allantoin with a yield of 69.6%, but the catalyst needs to be handled and the production cost is high

[0006] The synthetic method of prior art allantoin has: (1) uric acid potassium permanganate oxidation method, this method uses potassium permanganate as oxidant, and reaction belongs to strong oxidation reaction, is difficult for control, is not suitable for large-scale production, and uric acid cost (2) Calcium glyoxylate hydrochloric acid dissolving method, this method is carried out in two steps, first prepares calcium glyoxylate, then acidifies with hydrochloric acid and condenses with urea to generate allantoin, this method needs strong acid and strong Alkali is not easy to operate, and the yield is low, so it is not suitable for large-scale production; (3) urea dichloroacetic acid heating method, this method generates allantoin in one step, but the reaction needs methanol as a solvent, and needs to be heated at 40 ° C to 50 ° C, There is a danger of explosion in the reaction process, and the reaction needs vacuum distillation, complicated operation, and low yield, which is not suitable for large-scale production; (4) urea-glyoxylic acid condensation method, which is generally used by current allantoin manufacturers The method, which produces allantoin through one-step condensation of allantoin and glyoxylic acid, uses traditional protonic acids such as sulfuric acid, phosphoric acid, hydrochloric acid and other strong acids and mixed acids with different proportions of protonic acids as catalysts to obtain relatively high yields. production rate, and has the advantages of simple operation, easy to obtain raw materials, and relatively high yield, but these routes also have the problems of high acidity of the synthetic mother liquor and difficult treatment of the three wastes

Images