| abstract |
The present invention describes a process for the catalytic reduction of nitro-aromatic compounds by transfer of hydrogen from alcohols to nitro-aromatic compounds, said reduction being catalyzed by iridium complexes and characterized in that a primary or secondary alcohol having the formula (I) or a glycol:n is made to react with a nitro-aromatic compound having the formula (II):n wherein:n R and R', possibly linked to each other according to homo- or heterocycles, represent indifferently either a hydrogen atom or a possibly substituted hydrocarbylic group having up to 30 carbon atoms; Ar represents an aryl or hetero-aryl group, also substituted with inert groups; x and y, either equal to or different from each other, represent an integer chosen from 1 and 2, in the presence of a complex catalyst of iridium chosen from among those having formulae (III) and (IV):n andn wherein:n Chel represents a kelating bi-toothed nitrogeneous compound; L-L represents a molecule of a diolefine, preferably not conjugated; L represents a mono-olefine molecule; X - represents an anion chosen from among: Cl - , Br-, I - , PF 6 - , BR4-, ClO 4 - , B(C 6 H 5 ) 4 - , OH - ,n wherein R and R' have the significance already given to them; Y is a halogen, preferably Cl, Br or I; and optionally with a compound chosen from mineral alkaline compounds, at a temperature comprised between about 20°C and the boiling temperature of the reaction mass. n The compounds thus obtained consist of the derivatives of the partial or total hydrogenation of the nitro-aromatic starting compounds constituted by anilines or aryl-amines in general, by the aryl-hydroxyl-amines, by the aryl-hydrazo compounds and by the aryl-azo compounds, and can be used as intermediates for organic syntheses in general, in the field of fine chemistry. |