Process for the industrial preparation of water insoluble azo dyestuffs containing cyano groups from the corresponding halogen compounds

Abstract

A process for the manufacture of a cyano azo dyestuff insoluble in water, of the formula (I) (CN).sub.n --A--N.dbd.N--B (I) from a halogenated azo compound of the formula (II) (Hal).sub.n --A--N.dbd.N--B (II) in which A denotes a benzene radical carrying one or more nitrile or halogen substituents in the ortho position with respect to the azo group, Hal represents a halogen atom, in particular bromine, chlorine or iodine, B denotes the radical of a coupling component, preferably a substituted para-amino arylene radical, A and B are free from water-solubilizing groups and may carry other substituents usual in azo dyestuffs, n is 1 or 2, characterized in that a compound of formula (II) is reacted with an alkali metal cyanide, preferably sodium cyanide, and the operation is effected in the absence of water and in a solvent formed by a thioether of the formula (III) X--R--S--R'--H (III) where R and R' are the same or different and denote an alkylene radical having from 1 to 8 carbon atoms, a straight or branched chain able to contain an --O-- or --S-- bridge and in the presence of a catalyst constituted by a combination between the thioether of formula (III) and a cuprous salt.

Dependencies are inferred from the claim text.