摘要
本工作制备了数种高分子-镍(Ⅱ)配合物并用NaBH_4、LiAlH_4、甲醛氨水溶液或分子氢使之还原。研究结果表明,高分子—镍(Ⅱ)配合物难以用LiAlH_4或甲醛还原,而用氢气或NaBH_4还原后的配合物在较高温度(100～120℃)及一定的压力(3～6MPa)下还原硝基化合物及醛、酮类化合物时具有一定的催化活性,其中以NaBH_4还原的配合物活性最高。硝基化合物被还原为相应的胺,无副产物,醛、酮类还原为相应的醇,未发现氢解产物,说明催化剂有较高的选择性。此外还研究了腈类的加氢反应。
Some crosslinking polymer ligands containing oxygen, nitrogen and sulfur atoms and their nickel (Ⅱ ) complexes have been prepared. These complexes were reduced with several kinds of reducing agents including sodium horohydride ( NaBH4 ) at 0 ℃, molecular hydrogen at 150℃ and 6 MPa, lithium aluminium hydride ( LiAlH4 ) at 0℃ under nitrogen and formaldehyde in basic media. It has been found that the polymer-Ni (Ⅱ ) complexes were very difficult to be reduced by LiAlH4 and formaldehyde and the complexes reduced with these reducing agents showed no activity for the hydrogenation of nitro compound. In contrast, the complexes after reduction with NaBH4 or hydrogen exhibited relatively high activities and the former showed much higher activities than that of the latter. From the data of X-ray photoelec-tron spectrum, it can be seen that the Ni ( Ⅱ ) of polymer-Ni (Ⅱ ) complexes was converted into nickel boride after reduction by NaBH4. Also the complexes reduced by NaBH4 have very high selectivities. It has been found that when the complexes were used to catalyze the hydrogenation of nitro compounds, aromatic and aliphatic aldehydes and aromatic ketones, the high selectivity of the complexes turned these substances into corresponding amines and alcohols with no byproduct being detected in GLC analysis. One thing should be mentioned is that the complexes showed no activity towards aliphatic ketone such as methyl ethyl ketone under the same conditions. Also the hydrogenation of nitriles has been investigated.
Besides the high activities and selectivities, the polymer-Ni complexes reduced with NaBH4 have favorable stabilities comparing with inorganic nickel catalysts. They can be operated in the open air and keep their activities and selectivities after standing for three months without special protection.
出处
《分子催化》
EI
CAS
CSCD
1991年第3期241-247,共7页
Journal of Molecular Catalysis(China)
基金
中国科技大学结构分析开放实验室部分资助
