Ma Jiang-quan
2000
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Journal
Journal of Jiangsu Institute of Petrochemical Technology
Abstract
Allantoin acid was produced by condensating glyoxylic acid (prepared by means of oxidation glyoxal with nitric acid, without separation) with urea in the presence of nitro-sulfuric acid catalyst. The influences of the molar ratio of urea to glyoxylic acid ,reaction temperature,reaction time , the quantity and composition of catalyst on the yield of product were investigated. The optimum synthetic conditions were urea/glyoxylic acid molar ratio 5∶1,sulfuric acid/nitric acid molar ratio 8∶1,nitro-sulfuric acid catalyst/glyoxylic acid molar ratio 0 5∶1,reaction time 3h and reaction temperature 75℃.Under the optimum conditions,the yield of allantoin was 59 3%,the purity of allantoin over 98 5%.Through melting test,elementary analysis and spectrum of IR, the constitutional formula of allantoin was proved.