Hydrogenation of Acetophenone Promoted by Ruthenium Complexes of Modified Glucosamine Derivatives

The glucosamine acetal derivative L1 and sulfonamide derivatives L2-L4 were synthesized via the reaction of hydroxy and/or amine of glucosamine. The catalytic properties of the catalysts generated in situ from the reaction of Ru(II) compounds with glucosamine based ligands were evaluated in the hydrogenation of acetophenone with i-PrOH as hydrogen source. The catalytic activity was enhanced by the introduction of organic group into the glucosamine frame. The effects of reaction temperature, time, molar ratio of acetophenone to catalyst and base on the catalytic reaction of the hydrogenation of acetophenone promoted by the combination of RuCl2 (PPh3)(3)/L4 were explored. The turn over frequency(TOF) was up to 1232 h(-1) at 413 K with n(catalyst) n(KOH) n(acetophenone) = 1 : 10 : 5000. Among the bases used, the potassium isopropoxide was the best one to activate the precatalyst. The kinetic results revealed that the reaction was the first order respect to acetophenone, and the apparent activition energy was 37. 13 kJ/mol. The catalyst system of RuCl2(PPh3)(3)/L4 was stable in the hydrogenation of acetophenone. The plausible reaction mechanism was proposed.