Hydrogenetion of 4-Nitro-2'-Hydroxy-5'-Methylazobenzene on Supported Palladium Catalysts and Skeletal Nickel

A study is performed of the hydrogenation of 4-nitro-2'-hydroxy-5'-methylazobenzene on skeletal nickel and palladium catalysts supported on carbon in aqueous solutions of 2-propanol of various compositions. Approaches are developed to selective control of the transformation of substituted nitroazobenzenes containing two reactive groups in the molecule under conditions of hydrogenation. It is established that the rate of transformations of intermediate products is largely determined by activation of the nitro and azo groups and the completeness of their reduction under hydrogenation conditions. Rates of the hydrogenation of nitro and azo groups in individual compounds and in 4-nitro-2'-hydroxy-5'-methylazobenzene are compared in aqueous solutions of 2-propanol of various compositions on skeletal nickel and supported palladium catalysts.