Abstract: A process for the preparation of azo dyes of formula ##STR1## wherein K is the radical of a coupling component of the benzene or naphthalene series or of the heterocyclic series, and the hydroxy group is attached to K adjacent to the azo group, X is hydrogen or nitro and M is an alkali metal ion or an ammonium ion, which process comprises coupling a diazo component of formula ##STR2## in the presence of a zinc salt and in an inert gas atmosphere, to a coupling component of formula ##STR3## in which formula (2) and (3) above K and X are as defined for formula (1). The process makes it possible to obtain the azo dyes in high yield.

Abstract: A process for the preparation of an azo dye of formula ##STR1## wherein K is the .beta.-naphthol radical, X is hydrogen or nitro and M is an alkali metal ion or an ammonium ion, which process comprises coupling an aqueous solution containing 15 to 30 percent by weight of a diazo component of formula ##STR2## and 6 to 20 mol % of an ammonium salt, based on the molar amount of the diazo component, at a pH in the range from 10.5 to 11.5 and in an inert gas atmosphere, to a coupling component of formula ##STR3## in which formulae (2) and (3) above K and X are as defined for formula (1).The present invention makes it possible to obtain the claimed azo dyes in high yield.