Preparation of reactive phthalocyanine dyes

In a process for preparing reactive metal-free or metal-containing phthalocyanine dyes with one or more ethylsulfonyl groups substituted in the .beta.-position by an alkali-detachable radical or vinylsulfonyl groups as the reactive groups by reacting a metal-free or metal-containing phthalocyaninesulfonyl chloride with primary or secondary amines having one or more ethylsulfonyl groups substituted in the .beta.-position by an alkali-detachable radical or vinylsulfonyl groups and with or without further primary or secondary amines of the aliphatic, aromatic or heterocyclic series in the presence of a catalyst, the improvement which comprises carrying out the reaction in the presence of a catalyst comprising a heterocycle selected from the group consisting of 1-(C.sub.1 -C.sub.4 -alkyl)imidazoles in which the alkyl group may be C.sub.1 -C.sub.4 -alkoxy-substituted, 1-carboxymethylimidazole, 1,2-dimethylimidazole, 1-methylimidazole-5-carboxylic acid, 1-carboxymethyl-1,3,4-triazole and dimethyltetrazole.