The present invention relates to novel reactive dyes of formula I, (I), in which the variable independently denote X hydrogen, NO2, or NR3R4, Y NR5R6, OR7, SR8, or SO2R9 or a group suitable as a leaving group under the conditions of nucleophilic, aromatic substitution, R1 to R9 independently hydrogen, C1–C8 alkyl, C2–C8 alkyl, in which non-adjacent CH2 groups can be replaced by oxygen atoms, imino groups, or C1–C4 alkylimino groups, and/or CH2 groups may be replaced by carbonyl groups, C2–C8 alkenyl, or a group containing an active site or the precursor of an active site, with the proviso that at least one group R1 to R9 is present which contains an active site or the precursor of an active site. The present invention also relates to the use of the reactivedyes of formula I for dyeing substrates containing nucleophilic groups, and to compositions containing at least one reactive dye of formula I.