The present invention refers to dyestuffs of the formula (I) wherein R1 is H or (C1–C4)-alkyl; R2 is H or (C1–C4)-alkyl; each of X1 and X2, independently, is a labile atom or group; and M is H, an alkali metal, an ammonium ion or the equivalent of an alkaline earth metal, wherein compounds wherein R1 and R2 are H are excluded, mixtures of the dyestuffs of the formula (I) with dyestuffs of the formula (II) wherein each of X3 and X4, independently, is a labile atom or group; L is an organic linking group; and M is H, an alkali metal, an ammonium ion or the equivalent of an alkaline earth metal, processes for the preparation of said dyestuffs and said dyestuff mixtures and their use for dyeing and printing hydroxy- and/or carboxamido-containing fiber materials.