【摘要】 研究了以乙醛、硝酸、尿素为原料经氧化反应、氯化钙沉淀分离和缩合反应合成尿囊素的方法。考察了反应物配比、反应温度、时间等因素的影响 ,确定了氧化反应最佳条件 :n(乙醛 ) :n(硝酸 ) =0 .6 :1,反应温度 5 5℃ ,时间 6h ;缩合反应最佳条件 :n(乙醛酸钙 ) :n(盐酸 ) =1:2 .6 ,反应温度 70℃ ,时间 3h ,尿囊素总收率 2 8.0 % (以乙醛计 )。更多还原

【Abstract】 A process for preparation of allantoin from acetaldehyde,nitric acid and urea was studied,which comprises three steps:a)oxidation of acetaldehyde to glyoxalic acid by nitric acid;b)separation of glyoxalic acid as its calcicum salt by using CaCl 2 as precipitant;c)condensation of calicium glyoxylate with urea to allantoin under acidic condition.The effects of molar ratio of reactants,reaction temperature and time were investigated.The optimun reaction temperature and time were determined as following:oxidation:n(acetaldehyde):n(nitric acid)=0.6:1,reaction temperature and time:55℃ and 6h,respectively;condensation:n(calcium glyoxylate):n(Hydrochloric acid )=1∶2.6 reaction temperature and time:70℃ and 3h ,respectively.The total yield of allantoin reach to 28.0%(based on acetaldehyde).更多还原