Reduction of carbonyl compounds by Raney Ni–Al alloy and Al powder in the presence of noble metal catalysts in water

Raney Ni–Al alloy was found to be capable of reducing benzophenones to the corresponding diphenylmethanes (2) in water in good to excellent yields within 3 h at 60 °C in a sealed tube. The complete reduction process of both aromatic rings required 18 h at 80 °C with Raney Ni–Al and Al powder in the presence of Pt/C. The nature of the hydrogenated products was also found to greatly depend on temperature, reaction time, volume of water, and amount of Raney Ni–Al alloy being used.

The reduction of benzophenones has been carried out in water in a sealed tube at a lower temperature. In our experiment, Raney Ni–Al alloy reduced benzophenones to the corresponding diphenylmethanes in high yields within 3 h at 60 °C. On the other hand, Pt/C with Al powder and Ni–Al alloy gave significant results at 80 °C, realizing within 18 h the complete reduction of both aromatic rings of benzophenones.Figure optionsDownload as PowerPoint slide