Process for the preparation of reactive dyestuffs

Abstract

The invention relates to an improved process for the preparation of dyestuffs based on at least one triphendioxazine which is linked to a further chromophore via a triazine at a pH of 5.5 to 2.0 and a temperature of 50 to 100.degree. C.

Description

The invention relates to a process for the preparation of reactive dyestuffs.

Triphendioxazine dyestuffs in which 2 chromophores are linked via a triazine ring are disclosed in US-A-4,005,551. The process for preparing them is needy of improvement.

The object of the present invention is to provide an improved preparation process.

The invention relates to a process for the preparation of dyestuffs of the formula ##STR1## characterized in that a compound of the formula ##STR2## is condensed with a dyestuff of the formula ##STR3## in aqueous medium and in a pH range from 5.5 to 2.0, in particular 5.0 to 2.5, and at a temperature of 50 to 100.degree. C., in particular 70 to 80.degree. C., to give a dyestuff (I), in which

F denotes the radical of a triphendioxazine dyestuff, preferably

F denotes ##STR4## R independently of one another denotes hydrogen, C.sub.1 -C.sub.4 -alkyl or substituted C.sub.1 -C.sub.4 -alkyl

R' denotes hydrogen or a customary substituent of a triphendioxazine dyestuff, in particular halogen, alkyl, alkoxy, carboxyl

T.sub.1, T.sub.2 denote hydrogen, chlorine, bromine, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, phenyl or phenoxy, which may be substituted F.sub.1 denotes the radical of a chromophore.

Examples of R are: CH.sub.3, C.sub.2 H.sub.5, n-C.sub.3 H.sub.7, i-C.sub.3 H.sub.7, n-C.sub.4 H.sub.9, n-C.sub.6 H.sub.13, which may be substituted, for example, by OH, OCH.sub.3, OC.sub.2 H.sub.5, COOH, SO.sub.3 H, OSO.sub.3 H, CN, Cl.

Examples of substituents of the optionally substituted C.sub.1 -C.sub.4 -alkyl and C.sub.1 -C.sub.4 -alkoxy radicals T.sub.1 and T.sub.2 are C.sub.1 -C.sub.4 -alkoxy or OSO.sub.3 H.

Examples of substituents of the optionally substituted phenyl and phenoxy radicals T.sub.1 and T.sub.2 are Cl, Br, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy and SO.sub.3 H.

Examples of suitable substituents R' are the following: halogen, such as Cl, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, COOH.

The sulpho group in (IIIa) is in the. opposition relative to the substituent ##STR5##

F.sub.1 preferably denotes a chromophoric radical from the azo, formazan, anthraquinone, phthalocyanine or triphen-, dioxazine dyestuff series, in which the imino group ##STR6## is bound directly to an aromatic-carbocyclic or aromatic-heterocyclic C atom in F.sub.1.

Preference is given to the preparation of dyestuffs (I) in which R is hydrogen and F.sub.1 denotes a radical F. Particular preference is given to the preparation of dyestuffs (I) in which F.sub.1 is identical to F and in which R' represents hydrogen and T.sub.1 and T.sub.2 represents chlorine.

The dyestuffs (II) are obtained by a half-sided condensation of dyestuffs of the formula

F--H with cyanuric chloride, such as disclosed, for example, in DE-A-4,005,551, Example 1.

Dyestuffs of the formula (III) are known from the literature in large numbers.

Examples are: ##STR7##

The dyestuffs (II) are preferably used in the form of their lithium salts. Preferably, the reaction is carried out in the presence of a buffer suitable for the pH range from 2.0 to 5.5.

EXAMPLE 1

A neutral solution of the dilithium salt of 2,9-diamino-6,13-dichloro-triphendioxazine-disulphonic acid in 600 ml of water is added at room temperature to 0.05 mol of the di-lithium salt of the dyestuff of the formula ##STR8## (obtainable by condensation of the di-lithium salt of 2,9-diamino-6,13-dichloro-triphendioxazine-disulphonic acid with cyanuric chloride in the presence of lithium hydroxide) present in 700 ml of water. The pH is brought to 5.0 with 2 ml of phosphoric acid, and the reaction mixture is then heated to 75.degree. C. During condensation, the pH drops to about 2.5 to 3. After about 8 to 10 hours, the reaction is complete. The pH is then brought to pH 7 with lithium hydroxide solution. The dyestuff is precipitated by adding about 4% by volume of sodium chloride and can be isolated by filtering it off with suction.

In the form of the free acid, it has the formula ##STR9##

EXAMPLE 2

10 g of cyanuric chloride are added to 0.1 mol of 2,9- diamino-6,13-dichloro-triphendioxazine-disulphonic acid, which is dissolved in 1.3 l of ice water as the neutral di-lithium salt, and condensed in a pH range from 5 to 5.5, which is maintained by dropwise addition of dilute lithium hydroxide solution. After about 3 to 4 hours, 50% of the triphendioxazine dyestuff have been acylated on half a side. The mixture is heated to 72 to 74.degree. C, during which the pH is allowed to drop to 3.5 and then maintained at 3.5 to 4.5 by adding dilute lithium hydroxide solution. After about 8 to 10 hours, condensation is complete. The mixture is brought to pH 7 and the dyestuff is salted out with 4 % by volume of sodium chloride. The dyestuff is identical to the product obtained according to Example 1.

Claims

1. Process for the preparation of dyestuffs of the formula ##STR10## in which F corresponds to the formula ##STR11## wherein R' denotes hydrogen or a customary substituent of a triphendioxazine dyestuff,

T.sub.1 and T.sub.2 denote hydrogen, chlorine, bromine, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, phenyl, or phenoxy, which may be substituted,

R, independently of one another, denotes hydrogen, C.sub.1 -C.sub.4 -alkyl, or substituted C.sub.1 -C.sub.4 -alkyl, and

F.sub.1 denotes the radical of a chromophore,

whereby a compound of the formula ##STR12## in the form of its lithium salt is condensed with a dyestuff of the formula: ##STR13## in aqueous medium and in a pH range from 5.5 to 2.0 and at a temperature of 50 to 100.degree. C.

2. Process according to claim 1, characterized in that the reaction is carried out in the presence of a buffer.

3. Process according to claim 1, characterized in that

R is CH.sub.3, C.sub.2 H.sub.5, n-C.sub.3 H.sub.7, i-C.sub.3 -H.sub.7, n-C.sub.4 H.sub.9, n-C.sub.6 H.sub.13, which may be substituted by OH, OCH.sub.3 OC.sub.2 H.sub.5, COOH, SO.sub.3 H, OSO.sub.3 H, CN, Cl,

R' is Cl, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, COOH.

4. Process according to claim 1, characterized in that

R is H,

F.sub.1 is F,

R' is H,

T.sub.1, T.sub.2 are Cl

5. Process according to claim 1, characterized in that the dyestuff in the form of the free acid has the following formula ##STR14##