Fibre reactive scarlet azo dyes

1. 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.

2. A dyestuff as claimed in claim 1 , wherein X 1 and X 2 are halogen.

3. A dyestuff as claimed in claim 1 , wherein M is H or an alkaline metal.

4. The dyestuff as claimed in claim 2 , wherein M is hydrogen or sodium and X 1 and X 2 are chlorine.

5. The dyestuff as claimed in claim 4 , wherein 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 H, or sodium; and

# indicates the bond to the azo group in formula I.

6. The dyestuff as claimed in claim 1 , wherein D is a group of the formula IVa

wherein M, Ar 1 and * are defined as given in claim 1 .

7. The dyestuff as claimed in claim 5 , wherein D is a group of the formula IVa

wherein

M is H or sodium;

Ar 1 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; and

* indicates the bond to the NR 1 group of formula I.

8. The dyestuff as claimed in claim 6 , wherein Ar 1 is a group of the formula IIa or IIb

wherein M is H, an alkali metal, an ammonium ion or the equivalent of an alkaline earth metal.

9. The dyestuff as claimed in claim 7 , wherein Ar 1 is a group of the formula IIa or IIb

wherein M is H or sodium.

10. The dyestuff as claimed in claim 1 , wherein the dyestuff of formula (I) is of the formula Ia

wherein B is H or SO 3 M;

M is H, an alkali metal, an ammonium ion or the equivalent of an alkaline earth metal.

11. The dyestuff as claimed in claim 1 , wherein the dyestuff of formula (I) is of the formula Ib

wherein B is H or SO 3 M;

M is H, an alkali metal, an ammonium ion or the equivalent of an alkaline earth metal.

12. A process for preparing a dyestuff of formula I as claimed in claim 1 , which comprises reacting a piperazine compound of the formula VI

wherein R 3 , R 4 , R 5 , a, b, x, y, and z are defined as given in claim 1 , with a compound of the formula VII

wherein B, M, R 2 , X 2 and Ar are defined as given in claim 1 and X 3 is a labile atom or a group capable of reaction with an amine,

and with a compound of the formula VIII

wherein D, R 1 and X 1 defined as given in claim 1 and X 4 has one of the meanings of x 3 .

13. The process as claimed in claim wherein X 3 is chlorine.

14. A process for dyeing and printing hydroxy-containing fiber material and/or carboxamido-containing fiber material which comprises contacting the fiber material with the dyestuff as claimed in claim 1 .