SYNTHESIS OF O-AMINOPHENOLE BY POTENTIAL CONTROLLED HYDROGENATION OF O-NITROPHENOLE IN STIRRED AUTOCLAVES ON SUSPENDED NI SIO2-CATALYSTS/

o-Aminophenole was produced through reduction of o-nitroplenole by mea ns of gaseous hydrogen under middle pressure at a temperature of 363 K in an ethanolic Ni-catalyst's suspension. The maximum value of the ca talyst's electrochemical potential (measured by a special combined ele ctrode) was kept at a defined level by controlling the o-nitrophenole feed stream. Under these conditions (''potential controlled hydrogenat ion''), at ppm-concentrations of the nitro compound, sufficient and st able catalytic activity values of > 100 g amine per g catalyst and hou r can be achieved. The o-aminophenole can be isolated very easily by d ecantation and cooling down the product solution.