Preparing concentrated azo dye solutions using nitrite salt as both coupling component and diazotizing agent

摘要

Concentrated, stable solutions, with a low salt content, of cationic azo dyestuffs of the formula <IMAGE> (I) wherein A denotes the radical of an aromatic-carbocyclic or aromatic heterocyclic diazo component, R denotes alkylene, R1 denotes hydrogen or alkyl, R2 denotes alkyl, alkenyl or aralkyl, R3 denotes alkyl, R4 denotes hydroxyalkyl having 2 or more C atoms, R5 denotes halogen, alkyl, alkoxy, aryloxy, acyl or acylamino, m denotes 0, 1, 2, 3 or 4, and An- denotes a carboxylate ion, and wherein the cyclic and acyclic substituents can carry further non-ionic substituents, are prepared by the reaction of amines of the formula A-NH2 with coupling components of the formula <IMAGE> in aqueous carboxylic acids and, if appropriate, organic water-soluble solvents.