Process for the preparation of metallizable monoazo dyes in the presence of ketones

A process for the preparation of azo dyes of the formula ##STR28## in which A is benzene or naphthalene which is unsubstituted or substituted by nitro, halogen, sulfo, C.sub.2 --C.sub.6 alkanoylamino, C.sub.1 -C.sub.6 alkoxycarbonylamino, sulfonamido and sulfone groups and B is benzene which is monosubstituted or disubstituted by C.sub.1 -C.sub.6 alkyl, or naphthalene which is unsubstituted or substituted by amino, phenylamino, C.sub.1 -C.sub.6 alkylamino and sulfo, or 1-phenyl- 3-methyl-5-pyrazolone which is unsubstituted or substituted by halogen, C.sub.1 -C.sub.6 alkyl o C.sub.1 -C.sub.6 alkoxy, these radicals being bound to the azo group in the o-position with respect to the hydroxyl groups, which comprises:

• (a) diazotizing in aqueous solution an amine of the formula ##STR29## in the presence of a mineral acid, (b) coupling the product of step (a) onto a coupling component of the formula ##STR30## at a pH of about 7.0 to 8.5 and (c) accelerating the process by carrying out steps (a) and (b) in the presence of at least one ketone of the formula ##STR31## in which R.sub.1 and R.sub.2, independently of one another, are each C.sub.1 -C.sub.4 alkyl, said ketone being present in a 3 -to 12-fold molar amount relative to the molar amount of the amine of formula (2).