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

开发了用于前手性酮和前手性烯烃加氢反应的高选择性对映异构体催化剂。1.前手性烯烃对映体差异化氢化反应以三甲酸为底物，考察了催化剂的制备条件和反应条件。钯是该反应的最佳金属。所使用的制备方法如下。(I)对乙酰丙酮的分解，(Ii)用硝酸钯浸渍，(Iii)用硼氢化钠还原浸渍的氯化钯。结果表明：1.采用第三种方法制备的α-氧化铝或二氧化钛负载的Pd催化剂，经肉豆碱修饰后，在钛酸加氢反应中表现出最高的对映体过量。以乙酰丙酮镍为原料制备了负载型镍催化剂，并在含有酒石酸和溴化钠的溶液中进行了修饰。考察了催化剂制备条件对乙酰乙酸甲酯对映异构氢反应光学收率的影响。以沸石为载体时，光学收率最高可达86%。X射线衍射和透射电子显微镜分析表明，镍微晶尺寸约为0.50 nm，获得了较高的光学产率。

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.