Patent attributes
Anionic monoazo dyes of the formula (1) in which A represents 1- or 2-naphthyl residue, which is substituted by a total of one or two sulphonic and/or carboxylic acid groups. R1 represents hydrogen or C1-C4alkyl, each D1 and D2, independently of the other, represent either an amino acid residue resulting from removal of a hydrogen atom from the amino group of the amino acid or the residue —NR2R3, in which each R2 and R3, independently of the other, represent hydrogen, C1-C4alkyl, C2-C6alkyl which is substituted by hydroxy, halogen or cyano, phenyl which is unsubstituted or monosubstituted by hydroxy, halogen, SO3H, C1-C4alkyl or C1-C4alkoxy or alternatively, R2 and R3, together with the nitrogen atom to which they are connected, complete a saturated 5- or 6-membered ring which may contain, in addition to the nitrogen atom, one nitrogen or oxygen atom and which may be further substituted and n is 0 or 1, a process for their preparation and the use of these dyes for dyeing natural or synthetic materials, in particular, paper
