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AssigneeCiba-Geigy Corporation
InventorsHorst Langfeld, Claudio Puebla, Gunter Sereinig
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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, which process comprises coupling a diazo component of formula ##STR2## in the presence of one or more buffer mixtures and in the absence or presence of an alkali metal chloride, to a coupling component of formula ##STR3## in which formulae (2) and (3) K and X are as defined for formula (1). The present invention makes it possible to prepare the azo dyes in high yields.
A process for the preparation of an azo dye of formula ##STR76## wherein K is a benzene or naphthalene radical, 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, which process comprises coupling a diazo component of formula ##STR77## in the presence of one or more buffer mixtures, excepting the buffer mixture ammonium chloride/ammonia, and in the presence of an alkali metal chloride, to a coupling component of formula ##STR78## in which formulae (2) and (3) K and X are as defined for formula (1).
Dependencies are inferred from the claim text.