PROCESS FOR THE CATALYTIC REDUCTION OF NITRO-AROMATIC COMPOUNDS

摘要

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: is made to react with a nitro-aromatic compound having the formula (II): Ar-(NOy)x (II) wherein; R and R min , 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); {Ir Chel (L-L)}X (III) and Ir Chel (L)2Y (IV) wherein; 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<->, PF6<->, BR4<->, ClO4<->, B(C6H5)4<->, OH<->, wherein R and R min 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 DEG C and the boiling temperature of the reaction mass. 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.