Patent ID: 6946549

Claim:
A dyestuff of the formula I wherein each of R 1 , R 2 , R 3 , R 4 and R 5 , independently, is H or an optionally substituted alkyl group; each of X 1 and X 2 , independently, is a labile atom or group; B is H or SO 3 M; M is H, an alkali metal, an ammonium ion or the equivalent of an alkaline earth metal; Ar is a group of the formula II or of the formula III wherein Y is SO 3 M or an alkyl group, c is 0, 1 or 2, M is defined as given above and # indicates the bond to the azo group in formula I; D is a group of the formula IV wherein Ar 1 is defined as Ar, M is defined as given above and * indicates the bond to the NR 1 group of formula I; or D is a group of the formula V wherein R 6 is an alkyl group, B 1 is defined as B and M and * are defined as given above; each of x and y, independently, is 0 or 1 and at least one of x and y is 1; each of a and b is 2 to 5 and when each of x and y is 1, a>b; and z is 0, 1, 2, 3 or 4.