The Application Of Novel Cobalt And Nickel Catalysts In Hydrogenation Of Aromatic Ketones

Catalytic hydrogenation of ketones has become one of the most extensively studied area and the one of the most valuable synthetic methods for obtaining value-added product alcohols,which are significant intermediate in the production of pesticides,spices,pharmaceuticals.When hydrogen is used as hydrogen source,the cost is low and catalytic reaction usually has good enantioselectivity.Now the governing metals involved in the catalysts used for the catalytic hydrogenation are precious metals which are limited in resource,very expensive,toxic such as Ru,Rh,Ir,Pd.Compared with precious metal catalysts（Ru,Rh,Ir,Pd）,inexpensive metal catalysts（Fe,Co,Ni）are inexpensive,low-toxic,environmentally friendly,and rich in reserves.Recently,the application of iron catalysts in the hydrogenation of ketones has made progress to a certain extent.However,cobalt and nickel catalyst systems can be effectively used in hydrogenation of ketones are still rare.Using commercial available cobalt and nickel complexes as starting materials to combine with aminophosphine ligands to generate catalytic system used in the hydrogenation of ketones.Based on evaluation of its catalytic performance,continue to study the structure-activity relationship between catalyst structure and its properties,providing a valuable reference for the development of new and efficient low-cost mctal catalystsThis thesis consists of the following three parts:1.Combining different commercial available cobalt complexes with the ligands synthesized in our group to generate in situ catalytic system,then use them to catalyze the asymmetric hydrogenation of aromatic ketones.Among them,the（R,R,R ’,R ’）-P₂N₄/Co₄（CO）₁₂ system can catalyze the asymmetric hydrogenation of aromatic ketones efficiently,the enantioselectivity of product alcohols can up to 90%ee.2.Two kinds of novel nickel complexes were conveniently prepared under mild conditions by using inexpensive and readily available NiCl₂·6H₂O and amine phosphine ligands as starting materials,and at the same time single crystals were successfully obtained.Then they were characterized by X-single-crystal diffraction（X-ray）,infrared spectroscopy（IR）,high-resolution mass spectrometry（HRMS）and electron paramagnetic resonance（EPR）to determine its molecular structure.3.The nickel complexes were used to catalyze the hydrogenation reduction of aromatic ketones,the propiophenone was selected as model substrate to optimize the reaction conditions such as recation temperature,alkali amount,addition,initial hydrogen pressure.With the well-designed nickel（Ⅱ）complex P₂N₂-Ni,the hydrogenation of a wide range of ketones proceeded smoothly under relative mild reaction conditions,affording to the corresponding alcohols with high isolated yields,the isolated yield can up to 97%.