Design and Development of heterogeneous stereo-selective asymmetrically modified noble metal catalyst

本论文以顺芷酸为底物，研究了催化剂的制备条件和反应条件，并对催化剂的催化活性进行了考察。钯是该反应的最佳金属。使用的制备方法如下。(i)乙酰丙酮钯的分解，（ii）用硝酸钯浸渍，（iii）用硼氢化钠还原浸渍的氯化钯。通过第三种方法制备并用辛可尼定修饰的α-氧化铝或二氧化钛负载的Pd催化剂在惕各酸的氢化中得到最高的对映体过量。以乙酰丙酮镍为原料，制备了负载型镍催化剂，并在酒石酸和NaBr溶液中进行了改性。考察了催化剂制备条件对乙酰乙酸甲酯对映异构化加氢反应光学产率的影响。以分子筛为载体时，最大光学产率可达86%。XRD和TEM分析表明，获得了高的光学产率与镍晶粒尺寸约0.50 nm。

Highly selective enantio-differentiating catalysts were developed in the hydrogenation of prochiral ketones and prochiral alkenes.1 Enantio-differentiating hydrogenation of prochiral alkenesInvestigation of the catalyst preparation conditions and reaction conditions were carried out using tiglic acid as a substrate. Palladium was the best metal for this reaction. Preparation methods used are as follows. (i) decomposition of Pd acetylacetonate, (ii) impregnation using Pd nitrate, (iii) Reduction of impregnated palladium chloride by Sodium Borohydride. alpha-alumina or titania supported Pd catalysts prepared by the third method and modified with cinconidine gave the highest enantiomer excess in the hydrogenation of tiglic acid.2. Enantio-differentiating hydrogenation of prochiral ketonesSupported nickel catalysts were prepared from nickel acetylacetonate, and then modified in a solution containing tartaric acid and NaBr. The effect of the catalyst preparation conditions on optical yield were examined in the enantio-differentiating hydrogenation of methyl acetoacetate. The maximal optical yield of 86% was attained when zeolite was used as the support. XRD and TEM analyses indicated that high optical yields were attained with a nickel crystallite size of about .50 nm.