Fibre reactive formazan dyes, their preparation and their use

A process for the preparation of the reactive dye of formula (1), which comprises reacting with one another a compound of formula

• and a compound of formula
• X—CO—(CH2)m—SO2—Z2 (3)
• wherein X is a replaceable group,
• Z1 and Z2 are each independently of the other vinyl or a radical —CH2—CH2—Y and Y is a group removable under alkaline conditions,
• n is the number 1, 2, 3 or 4,
• m is the number 2, 3 or 4,
• q is the number 0 or 1, and
• the substituents —(SO3H)n, —SO2—Z1 and —NH2 are bound to the benzene rings A, B and/or C, and said benzene rings A, B and/or C are optionally further substituted by at least one substituent selected from the group C1-C4 alkyl, C1-C4 alkoxy and halogen.