New azo dyes

The invention comprises azo dyes containing, attached by way of a nitrogen atom, the radical of the formula in which R1 denotes a hydrogen atom or an alkyl, cycloalkyl, aralkyl or aryl group, R2 denotes a hydrogen atom or an alkyl, cycloalkyl, aralkyl or aryl group, E denotes a halogen atom, a quaternary ammonium group or an ester group the acid radical of which is derived from polybasic mineral acid or an organic derivative thereof and Y denotes a group of the general formula in which A denotes an alkylene radical or a substituted alkylene radical, Z1 denotes a hydrogen atom, a halogen atom or an alkyl group and Z2 denotes a hydrogen atom, a halogen atom or an alkyl group and processes for the preparation thereof wherein (a) an azo dye or an intermediate suitable for the production of an azo dye, which contains one or more reactive hydrogen atoms attached by way of nitrogen is reacted with an isocyanate of the general formula or with a corresponding compound capable of being converted into the isocyanate under the reaction conditions and, when a dye intermediate has been used completing the conversion of the reaction product to the azo dye, or (b) an azo dye or an intermediate suitable for the production of an azo dye, which contains one or more reactive hydrogen atoms attached by way of nitrogen, is reacted with an isocyanate of the general formula in which R1, R2 have the meanings given above, X denotes a halogen atom and X1 denotes a halogen atom or an OH group protected by an acyl radical capable of being split-off or with a corresponding compound capable of being converted into the isocyanate under the reaction conditions, the radical X1 in the reaction product is converted into a quaternary ammonium group when a halogen atom or into an ester group of which the acid radical is derived from a polybasic mineral acid or an organic derivative thereof when an OH group and, when a dye intermediate has been used the conversion of the reaction product to the azo dye is completed. Examples of compounds capable of being converted into isocyanates are carbamic acid halides, phenyl-carbamic acid esters and carboxylic acid azides. Among the isocyanates specified for use in the process are 1-chlorobut-2-ine-4-isocyanate and 1,2-dichloro-but-2-ene-4-isocyanate. The reactive hydrogen in the starting materials may be present in primary or secondary alkyl-amino, arylamino, alkyl- and arylh