A dye of the general formula (I) where D is the residue of a diazo component; X is (C1-C6)-alkylene or oxygen-interrupted (C2-C6)-alkylene; R1 is methyl, ethyl or phenyl; R2 is hydrogen, cyano or carboxamido; R3 is phenyl or substituted phenyl; R4 is hydrogen or methyl or R3 and R4 combine with the atoms to which they are attached to form a five- or six-membered ring. The invention further relates to the process of the preparation of the dye of formula and its use.