Development of the enantioselective solid catalyst with high enantioselectivity

对映体选择性固体催化剂在光学活性化合物的合成中具有重要意义，而光学活性化合物又是农用药物或农用化学品的重要中间体。本研究旨在开发具有高对映选择性和高耐久性的对映选择性固体催化剂，使回收的催化剂能够重复使用。本研究通过在镍表面吸附(R，R)-酒石酸和溴化钠制备了对映体选择性催化剂(这一过程称为改性)。提出了两种改性方法，一种是预改性(将镍催化剂浸泡在(R，R)-酒石酸和NaBr的溶液中，然后用水、甲醇和四氢呋喃洗涤，然后用于加氢反应)，另一种是原位改性(在反应介质中加入(R，R)-酒石酸和NaBr)。方法的类型显著影响对映体的选择性和耐受性。在本研究中，为了比较预修饰和…的特点在原位改性的基础上，考察了水溶液和有机溶剂中预改性条件的影响。以还原镍为基础镍催化剂。还原的镍是通过在氢气中还原氧化镍(商业上可获得的一种或一种通过在773K或137K下分解和焙烧氢氧化镍制备的)来制备的。结果表明，在水溶液中，以137K焙烧的氧化镍为原料制备的改性还原镍催化剂对映体选择性最高，达到88%。酒石酸和Br2+在催化剂表面的覆盖率分别为25%和13%。773K焙烧得到的改性还原镍对映体选择性为50%。酒石酸和Br^-在表面的覆盖率分别为17%和16%。另一方面，对于有机溶剂(THF)中的改性，研究表明，为了获得高的对映选择性和高的耐久性，必须在高温(高压釜中为373K)和高氢压(9 Mpa)下进行改性。在这种情况下，酒石酸和Br^-在表面的覆盖率分别为30%和38%。从这些结果来看，酒石酸在表面的覆盖率并不是决定对映体选择性和耐久性的唯一因素，文献中报道酒石酸是获得高对映体选择性的关键因素。镍的表面(基镍的类型)对于确定对映体的选择性也是非常重要的。研究还表明，高的Br^-覆盖率是重要的，特别是对于获得高的对映体选择性的持久性。较少

Enantioselective solid catalyst is important for the syntheses of optically active compounds, which are important for the intermediates for the farmaceuticals or agrochemicals. This study aims at the development of the enantioselective solid catalyst with a high enantioselectivity and its high durability in the repeated use of the recovered catalyst. In this study, enantioselective catalyst was prepared by adsorbing (R,R)-tartaric acid and NaBr on a nickel surface (this process is called modification). Two types of modification methods have been developed, that is i)pre-modification (nickel catalyst is soaked in a solution of (R,R)-tartaric acid and NaBr, is washed by water, methanol and THF, and then uses for the hydrogenation reaction), and ii)in-situ-modification ((R,R)-tartaric acid and NaBr are added to the reaction media). The type of methods significantly influence the enantioselectivity and its durability.In this study, for comparing the features of the pre-modification and tho … More se of the in-situ-modification, effects of the pre-modification conditions in an aqueous solution and in an organic solvent were investigated. As the base nickel catalyst, reduced nickel was used. The reduced nickel was prepared by the reduction of nickel oxide (commercially available one or one prepared by the decomposition and calcinations of nickel hydroxide at 773 K or 1373 K) in a hydrogen stream. As a results, for the modification in an aqueous solution, the modified reduced nickel catalyst prepared from nickel oxide calcined at 1373 K gave the highest enantioselectivity of 88%. The coverage of tartaric acid and Br^- on the catalyst surface was 25% and 13%, respectively. The modified reduced nickel prepared from nickel oxide calcined at 773 K gave the enantioselectivity of 50%. The coverage of tartaric acid and Br^- on the surface was 17% and 16%, respectively. On the other hand, for the modification in an organic solvent (THF), it was revealed that the modification at a high temperature (373 K in an autoclave) and a high hydrogen pressure (9 MPa) were mandatory for attaining a high enantioselectivity and its high durability. In this case, the coverage of tartaric acid and Br^- on the surface was 30% and 38%, respectively. From these results, the coverage of tartaric acid on the surface, which was reported as a crucial factor for attaining a high enantioselectivity in the literature, was not the only factor for determining the enantioselectivity and the durability. The surface of nickel (the type of base nickel) was also very important for determining the enantioselectivity. It was also revealed that a high coverage of Br^- was important, especially for attaining a high durability of the enantioselectivity. Less