Research On Aunpore-Catalyzed Selective Hydrogenation Of C=O In Cinnamaldehydes

Cinnamyl alcohols were widely used in the synthesis of flavor and pharmaceutical industries as important intermediates. The selective hydrogenation of cinnamaldehydes is one of the important methods for synthesis of cinnamyl alcohols. However,there is a great challenge in the selective hydrogenation of C=O in cinnamaldehyde in the thermodynamic and kinetic aspects.Selective hydrogenation of C=O group in cinnamaldehydes was investigated using AuNPore as catalyst, H₂ as the hydrogen source and a coordinating solvent to promote heterolytic cleavage of hydrogen to form H" and thereby slective hydrogenation of C=O in cinnamaldhyde.1.Slective hydrogenation of C=O in cinnamaldhyde was selected as the model reaction,the optimized reaction conditions: AuNPore（5 mol%） as catalyst,H₂（15 atm）,EtsN（3 mL）as the solvent,at 100 ℃ for 24 h. Under optimized reaction conditions, the selectivity of cinnamyl alcohol and its deritives were more than 90%.2.The results obtained shown that the reaction of a cinnamaldehyde bearing electrondonating group could proceeded smoothly to give an allylic alcohol in higher yield than that of reaction of a cinnamaldehyde bearing an electron—withdrawing group. A low yields were observed in the reactions of a—substituted cinnamaldehydes. When a cinnamaldehyde bearing unsaturated functional group such as cyano, only the C=O was selective hydrogenated. The activity of the catalyst did not decrease after reusing 5 times.