Abstract: The invention relates to a process for the preparation of 1:2 chromium, 1:2 cobalt, 1:2 nickel or 1:2 iron complex azo dyes diazotisation, coupling and metallizing, without isolation of the coupling product, which process comprises diazotizing at least one amine of the benzene or naphthalene series in aqueous solution and coupling the diazonium compound so obtained to at least one coupling component of the benzene or naphthalene series or of the heterocyclic series, such that the azo dye obtained as intermediate contains groups suitable for metal complex formation, and carrying out the diazotization or coupling in the presence of a chromium, cobalt, nickel or iron donor.The dyes obtained by the process of the invention are suitable for dyeing in particular wool or synthetic textile polyamide fibre materials as well as leather, and for use as wood mordant dyes.

Abstract: Amines which are sparingly soluble in water are diazotised by first preparing a melt or solution of said amines and then precipitating them from the melt or a solution in an organic solvent by adding water, and then diazotising the resultant suspension. In this procedure, the reaction times are appreciably shorter than those of conventional processes.

Abstract: The invention relates to a process for the preparation of azo compounds of the formula ##STR1## wherein K is the radical of a coupling component, R is a water-solubilising group and X is a fibre-reactive radical, and the benzene ring A may be further substituted, which process comprises reacting a compound of the formula ##STR2## in an aqueous medium containing 5 to 25% by weight of an alkali metal halide or alkali metal sulfate, based on the weight of the medium, with a compound which introduces the radical X to give the compound of the formula ##STR3## diazotising said compound direct and coupling the diazotisation product with a coupling component of the formulaH--K (4)in which formulae (2), (3) and (4) A, R, X and K are as defined for formula (1).

Abstract: The invention relates to a method of determining and controlling the diazonium ion concentration in diazotization solutions and/or in azo coupling reactions, which comprises determining said diazonium ion concentration by means of IR spectroscopy from the intensity of the N.tbd.N stretching frequency.The method is extremely selective and virtually trouble-free and permits the simultaneous determination of the concentration of different diazonium salts in mixtures.