Catalytic hydrogenation of aromatic nitro cpds. - in presence of excess hydrogen to minimise solubilisation of palladium catalyst

摘要

Hydrogenation of aromatic nitro cpds. (I) is carried out in presence of a supported Pd catalyst. The H2 needed for redn. is contained in the vicinity of the catalyst such that (a) there is always a stoichiometric excess of H2 relative to (I) and (b) some H2 is reversibly absorbed by the crystal lattice of the Pd. Pref. catalysts contain is not 15 (5-15)wt.% Pd and the support is esp. partly-activated porous active carbon of surface area 800 m2/g and mean partic dia. 10 mu. Used specifically for hydrogenating dinitrotoluene. Solubility of Pd in the reaction medium is reduced almost to zero.