CARBONYLATIVE REDUCTION OF NITROPHENOLS TO AMINOPHENOLS

Two- or three-component catalysts composed of (i) sulfur or sulfur com pound (H2S, CS2, COS, Na2S), (ii) basic additive (triethylamine, CH3ON a, Na2S), and usually (iii) vanadium(V) compounds (e.g. NH4VO3) were f ound to catalyze efficiently the reaction of CO + H2O with isomeric ni trophenols to give the corresponding aminophenols. The reaction procee ds smoothly al 398 and 483 K and initial pressure of 7 MPa, and its ra te increases from 2- to 4-nitrophenol. The selectivity to aminophenols exceeding 96 per cent was obtained at the water to nitrophenol molar ratio higher than 5. The solvents such as methanol and dioxane ensured better contact of the reactants, which was necessary for achievement of such a high selectivity. The effectiveness of the sulfur components (based on the S content) is expressed by the following sequence: S : CS2: Na2S : H2S : COS = 1 : 1.2 : 2.5 : 10 : 11. The reaction takes pl ace also under the reduced CO pressure to 0.1 - 0.35 MPa. Formation of side products and mechanism of the reaction are discussed.