Abstract: Azo dyestuffs, which in the acid form, are represented by the formula:A -- N .dbd. N -- M -- N .dbd. N -- E (1)whereinA is an aromatic radical,M is a 1,4-benzene radical which may be substituted,E is the residue of a coupling component which is free from azo groups,At least one of A and M containing a phosphonic acid group, and the metal complexes of those having a metallisable group are reactive dyes suitable for use in the process of German OLS No. 2324809.

Abstract: 1. Metal complex formazan dyestuffs which in the acid form are represented by the formula: ##STR1## wherein A and B are each selected from phenylene, naphthalene, substituted phenylene or substituted naphthalene groups, said substituted phenylene or substituted naphthalene groups containing at least one group selected from SO.sub.3 H, PO.sub.3 H.sub.2, CO.sub.2 H, CN, NO.sub.2, NH.sub.2, acetylamino, benzoylamino, OH, F, Cl, Br, C.sub.1-4 alkyl, C.sub.1-4 alkoxy, sulphonamido, ##STR2## wherein Y = CO or SO.sub.2 and n=0 or 1 or H.sub.2 O.sub.3 P--CH.sub.2 CH.sub.2 --NH--Y-- wherein Y = CO or SO.sub.2 ;D is NO.sub.2, CN, COOH, SO.sub.3 H, C.sub.1-4 alkyl, C.sub.1-4 alkyl substituted by PO.sub.3 H.sub.2 ; C.sub.1-4 alkenyl, styryl, pyridyl, furyl, COCH.sub.3, CO.sub.6 H.sub.5, naphthyl, phenyl or phenyl substituted by at least one group selected from COOH, NH.sub.2, CN, F, Cl, Br, acetylamino, benzoylamino, OH, methyl, methoxy, SO.sub.3 H and PO.sub.3 H.sub.2 ;X.sup.1 and X.sup.