Hydrogenation of Quinolines and Aldehydes Catalyzed by a Pyrolyzed, Augmented Cobalt-Salen Complex

Abstract

We report on the preparation and characterization of a robust and easy-to-handle composite catalyst based on an enlarged salcomine-type solution-phase precursor. Wet impregnation of silica with an extended, homobimetallic cobalt-salen complex followed by controlled pyrolysis of the imbued and dried support afforded the fully functional catalytically active material. The solid catalyst thus produced affected the heterogeneous hydrogenation of quinolines and aldehydes, which selectively gave 1,2,3,4-tetrahydroquinolines and primary alcohols, respectively. In order to showcase its versatility, our catalyst was tested under batch conditions in steel autoclaves as well as in a continuous flow reaction system, which produces the requisite hydrogen gas in situ through water electrolysis (H-Cube Mini Plus from ThalesNano). In both operating modes, we observed very good product yields and decent functional group tolerance.