Copper, Cobalt, Nickel and Iron Complexes of Disazo Dyes

The present invention relates to compounds which in the form of the free acids are of the general formula ##STR3## where A is a radical of the formula ##STR4## the radicals Y independently of one another are each hydroxyl or amino, X is hydrogen, hydroxysulfonyl or a radical of the formula

R is a radical of 1-aminonaphthalene-4-, -5-, -6-, -7- or -8-monosulfonic acid or of 1-aminonaphthalene-3,6-, -3,7-, -3,8-, -4,7- or -4,8-disulfonic acid, or a Cu, Fe, Ni, Co, Mn or Cr complex thereof, and D is phenyl which is unsubstituted or substituted by methyl, methoxy, ethoxy, nitro, chlorine, bromine or sulfo, or is sulfo-substituted naphthyl.

The compounds of the formula I can be prepared by reacting a compound of the formula ##STR5## with a diazo compound of an amine of the formula

and, if desired, converting the coupling product to a metal complex. The reactions are known in principle, and do not possess any special features compared with the preparation of known substances.

R is particularly preferably 4-, 6- or 8-sulfonaphthyl or the Fe complex.

Furthermore, Y is preferably hydroxyl and X is preferably hydrogen, and preferred dye mixtures are those containing a compound in which X is H with about 5-20% of a compound in which X is D--N.dbd.N--.

The compounds of the formula I are particularly useful for dyeing leathers, such as those retanned with vegetable or synthetic tanning agents. Fast brown dyeings are obtained.

In the Examples which follow, parts and percentages are by weight, unless stated otherwise.

19.9 parts of 1-amino-2-hydroxy-3,5-dinitrobenzene are diazotized in a conventional manner, and the product is coupled to 11 parts of resorcinol in a solution rendered alkaline with sodium carbonate. The diazonium salt obtained from 22.3 parts of 1-aminonaphthalene-4-sulfonic acid is then added to the suspension, at pH 8-9. After coupling is complete, the reaction mixture is brought to pH 5 with acetic acid, 38 parts of anhydrous iron(III) chloride are added, and the mixture is heated at 90.degree.-95.degree. C. for about 3 hours, at pH 4-5.

When metallization is complete, the dye is precipitated by the addition of sodium chloride, isolated and dried. The iron complex of the compound of the formula ##STR6## dyes leather in lightfast and wetfast yellowish brown hues.

The dyes listed in the Table below can be synthesized by the above method.

19.9 parts of 1-amino-2-hydroxy-3,5-dinitrobenzene are diazotized in a conventional manner, and the product is coupled to 11 parts of resorcinol in a solution rendered alkaline with sodium carbonate. The diazonium salt obtained from 22.3 parts of 1-aminonaphthalene-4-sulfonic acid is then added to the suspension, at pH 8-9. After formation of the diazo dye is complete, the diazo compound obtained from 21.8 parts of 1-amino-2-sulfo-4-nitrobenzene is added in such a manner that coupling takes place at a pH of from 6 to 7. When coupling is complete, the reaction mixture is brought to pH 5 with acetic acid, and complexing with anhydrous iron(III) chloride is carried out by a procedure similar to that described in Example 1.

When metallization is complete, the dye is precipitated by the addition of sodium chloride, isolated and dried. The iron complex of the compound of the formula ##STR17## gives lightfast and wetfast brown dyeings on chrome side leather retanned with vegetable or synthetic tanning agents.

The dyes listed in the Table below can be prepared by the above method.

23.4 parts of 6-nitro-2-amino-1-phenol-4-sulfonic acid are diazotized in a conventional manner, and the product is coupled to 11 parts of resorcinol in a solution which has been rendered alkaline with sodium carbonate. The diazonium salt obtained from 22.3 parts of 1-aminonaphthalene-4-sulfonic acid is then added to the suspension, at pH 8-9. When coupling is complete, the disazo dye is complexed with iron(III) chloride by a procedure similar to that described in Example 1, and the complex is isolated.

The iron complex of the compound of the formula ##STR35## dyes leather in yellowish brown hues with good tinctorial properties.

The dyes listed in the Table below can be prepared by the method described in Example 19.

23.4 parts of 4-nitro-2-amino-1-phenol-6-sulfonic acid are coupled to 11 parts of resorcinol in a conventional manner, in a solution rendered alkaline with sodium carbonate. The diazonium salt obtained from 22.3 parts of 1-aminonaphthalene-4-sulfonic acid is then added to the monoazo dye, at pH 8-9. When the formation of the disazo dye is complete, the product is coupled, at pH 6-7, to the diazo compound obtained from 11.1 parts of 1-amino-2-methoxybenzene, and the dye is then complexed with iron(III) chloride by a procedure similar to that described in Example 1, and the complex is isolated.

The iron complex of the compound of the formula ##STR45## dyes leather in yellowish brown hues with good allround fastness.

The dyes listed in the Table below can be synthesized by the above method.