2-Acetamidoacrylic acid or methyl 2-acetamidoacrylate is reacted with solution of sodium of methylselenol to give N-acetyl-Se-methylselenocysteine.The L(and D)-Se-methylselenocysteine have been prepared in high optica...2-Acetamidoacrylic acid or methyl 2-acetamidoacrylate is reacted with solution of sodium of methylselenol to give N-acetyl-Se-methylselenocysteine.The L(and D)-Se-methylselenocysteine have been prepared in high optical purity by treating N-acetyl-Se-methylselenocysteine in water using acylase I from porcine kidney as a catalyst.The influencing factors on the resolution reaction are discussed by orthogonal experiment,including pH value,reaction temperature,concentration of Co2+ and amount of acylase I.Under the optimizing resolution conditions,L(and D)-Se-methylselenocysteine are obtained with>96 % optical purity in about 40% yield.展开更多
目的:研究雷公藤两种活性成分雷酚内酯与5,5’-二甲氧基落叶松脂素的热稳定性,为探讨雷公藤煨制机理提供参考。方法:采用热重、微商热重和差热分析技术测得热分析曲线,综合多升温速率法和单一升温速率法进行动力学处理,计算热分解的表...目的:研究雷公藤两种活性成分雷酚内酯与5,5’-二甲氧基落叶松脂素的热稳定性,为探讨雷公藤煨制机理提供参考。方法:采用热重、微商热重和差热分析技术测得热分析曲线,综合多升温速率法和单一升温速率法进行动力学处理,计算热分解的表观活化能和指前因子对数值并推测理论贮存期。结果:雷酚内酯与5,5’-二甲氧基落叶松脂素均为一步失重分解,差热曲线均有两个吸热峰,为熔点峰和热分解反应最快峰。雷酚内酯热分解机制为二维扩散,表观活化能83.61 k J/mol,指前因子对数值14.39;5,5’-二甲氧基落叶松脂素分解机制为相界面反应,表观活化能105.20 k J/mol,指前因子对数值18.16。推测雷酚内酯和5,5’-二甲氧基落叶松脂素的理论贮存期均为3年。结论:雷酚内酯和5,5’-二甲氧基落叶松脂素热分解温度大于200℃,热分解活化能表明两者具有较高的热稳定性。因此,在雷公藤200℃煨制过程中,雷酚内酯和5,5’-二甲氧基落叶松脂素可能不发生变化。展开更多
文摘2-Acetamidoacrylic acid or methyl 2-acetamidoacrylate is reacted with solution of sodium of methylselenol to give N-acetyl-Se-methylselenocysteine.The L(and D)-Se-methylselenocysteine have been prepared in high optical purity by treating N-acetyl-Se-methylselenocysteine in water using acylase I from porcine kidney as a catalyst.The influencing factors on the resolution reaction are discussed by orthogonal experiment,including pH value,reaction temperature,concentration of Co2+ and amount of acylase I.Under the optimizing resolution conditions,L(and D)-Se-methylselenocysteine are obtained with>96 % optical purity in about 40% yield.
文摘目的:研究雷公藤两种活性成分雷酚内酯与5,5’-二甲氧基落叶松脂素的热稳定性,为探讨雷公藤煨制机理提供参考。方法:采用热重、微商热重和差热分析技术测得热分析曲线,综合多升温速率法和单一升温速率法进行动力学处理,计算热分解的表观活化能和指前因子对数值并推测理论贮存期。结果:雷酚内酯与5,5’-二甲氧基落叶松脂素均为一步失重分解,差热曲线均有两个吸热峰,为熔点峰和热分解反应最快峰。雷酚内酯热分解机制为二维扩散,表观活化能83.61 k J/mol,指前因子对数值14.39;5,5’-二甲氧基落叶松脂素分解机制为相界面反应,表观活化能105.20 k J/mol,指前因子对数值18.16。推测雷酚内酯和5,5’-二甲氧基落叶松脂素的理论贮存期均为3年。结论:雷酚内酯和5,5’-二甲氧基落叶松脂素热分解温度大于200℃,热分解活化能表明两者具有较高的热稳定性。因此,在雷公藤200℃煨制过程中,雷酚内酯和5,5’-二甲氧基落叶松脂素可能不发生变化。
