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采用奎宁修饰型Pt/A l2O3作为加氢催化剂在常温常压下比较了乙酸和甲苯溶剂中丙酮酸乙酯的不对称加氢与一般的加氢反应的反应结果;研究了反应对映选择性与底物转化率的关系、丙酮酸乙酯用量对产物对映选择性的影响、三乙胺的作用以及乙酸-甲苯混合溶剂的使用.实验结果表明,乙酸作为反应溶剂的性能优于甲苯且溶剂化作用强于甲苯;两种溶剂中的不对称加氢反应均存在初始过渡期,以乙酸为溶剂时,催化反应速度较快;在乙酸溶剂中底物用量对产物对映纯度影响不大,在甲苯溶剂中底物用量具有最佳值;在乙酸溶剂中加入三乙胺能显著提高反应的对映异构体选择性而在甲苯溶剂中则没有促进作用.
Quinine modified Pt / Al 2 O 3 was used as hydrogenation catalyst to compare the reaction results of asymmetric hydrogenation of ethyl pyruvate with normal hydrogenation reaction in acetic acid and toluene at room temperature and normal pressure. The effects of reaction enantioselectivity The relationship between the conversion and the substrate, the effect of ethyl pyruvate on the enantioselectivity of the product, the effect of triethylamine and the use of acetic acid-toluene mixed solvent.The experimental results show that the performance of acetic acid as the reaction solvent is better than that of toluene And the solvation was stronger than that of toluene. The asymmetric hydrogenation reaction in both solvents had the initial transitional period. When acetic acid was used as the solvent, the catalytic reaction rate was faster. The effect of the amount of substrate in the acetic acid solvent on the enantiomeric purity Large, the amount of substrate in toluene solvent has the best value; the addition of triethylamine in acetic acid solvent can significantly improve the enantioselectivity of the reaction without promoting role in toluene solvent.