On the Formation of Benzonitrile from Benzaldehyde and Ammonia. I. with Copper Catalysts

The mechanism of the oxidative formation of benzonitrile from benzaldehyde with ammonia in a methanol solution catalyzed by some copper compounds is discussed, as well as the dependence of the activity on the basicity of the catalysts. On the basis of such kinetic data as the rate of nitrile formation related to the concentration of cupric hydroxide as a catalyst, the effect of the water added, and the effect of the sodium hydroxide added, benzilideneimine was confirmed to be an important intermediate. The rate of nitrile formation could be explained fairly quantitatively on the assumption that aldehyde and ammonia react to produce benzilideneimine, from which is produced the corresponding nitrile via the imine radical. Cupric hydroxide, cuprous chloride, and cupric chloride with sodium hydroxide or sodium methoxide are active catalysts, but cupric acetate and cupric chloride are not so active. This difference is found to be due to the basicity of the catalysts. Some other results are also discussed.