CS236435B1 - Process for preparing a chromium complex of monoazo dye - Google Patents

Abstract

A method for preparing a chromium complex of a monoazo dye of the general formula by chromizing a semi-dye in an aqueous medium with the addition of 0.01 to 0.3 moles of mineral acid, based on 0.1 moles of chromium salt.

Description

The present invention is directed to the preparation of the chromium complex of the monoazobaring agent of the formula I

This complex is an intermediate product for the production of dyes suitable for dyeing wool, silk, polyamide and polyurethane fibers or mixtures thereof from weakly acid to neutral baths with high shade yellows. It can also be used for other purposes.

β

Said chromium complex is prepared by treatment with chromium salts not the starting monoazo dye in an aqueous medium at a temperature above 100 ° C (in a closed vessel) with the addition of 5 to 20% by weight. formic acid based on the weight of azo dye.

23B 435

The disadvantage of this process is, besides the long reaction time, the necessity to use a considerable excess of chromium salts and formic acid, which not only does not guarantee the quantitative course of chromation, but passes into the waste water during the isolation of the chromium complex.

It has now been found that these disadvantages are eliminated by the process for the preparation of the chromium complex, the monoazo dyes of the general formula I

where one of the four X's is -SO 4 H and the other three are hydrogen atoms, by chromating the monoazo dyes of formula II

X

3 236 435 wherein one of the four X is SO 4 H and the other three X are hydrogen atoms with chromium salts in an aqueous medium, according to the invention, in that the chromation is carried out with an addition of 0.01 to 0.3 mol of mineral acid based on 0 1 mol of chromium salt, optionally with the addition of 0.01 to 0.3 mol of formic acid.

Example 1 ..

A neutral mole suspension of the monoazo dye of 2-amino-4-sulfoberzoic acid and 1-phenyl-3-methyl-5-pyrazolorx (0.1 ml) is acidified with 0.1 mol of hydrochloric acid; 0.11 mol of chromium chloride was added and the reaction mixture was heated in a sealed kettle at 130 ° C for 3 hours.

After cooling, the precipitated crystalline complex is filtered off. 72 g of wet - 55 g of dry, crystalline, completely pure chromatographically is obtained.

Example 2 of

0.1 mole of monoazo dye-4-amino-5-sulfobenzoic acid ^and 1-phenyl-3-methyl-5-pyrazplonic acid are dissolved in 500 ml of water, acidified with 0.05 mole of sulfuric acid and 0.055 mole of Cr 2 SO 4 is added. Heat in a cauldron at 130 ° C for 3 hours.

After cooling, 62 g of wet = 52 g of dry, crystalline, chromatographic, uniform chromium complex were isolated by filtration.

Example 3

To 0.1 mole of a neutral to weakly acidic coupling ^x / solution (pH 5-7) with 2-aminobenzoic monoazobarvivay kyše- © 4238 lire 43S ai y 1 (4-sulfcfenyl) -3-methyl-5-pyrazolone volume

500 ml is added 55 g of potassium chromate alumina (= 0.1 mol

KCr (SO ₄ > ₂ * ¹² H 4 -O)> 17.8 g of formic acid 85 # (= 15.13 g of formic acid 100% - 0.33 mol) and 0.075 mol of acid

3olné ^? The suspension was heated to 110 ° C in a sealed kettle for 5 hours. After cooling, 61 g of wet = 53 g of a dry, crystalline, 1: 1 chromium complex are isolated by chromatography.

Example 4 of

Dissolve 0.1 mol of monoazo dye-1-aminobenzoic acid and 1- (3-sulfophenyl) -3-methyl-5-pyrazoloruise in 500 ml of water and adjust to pH 2.0 to 2.9 by addition of hydrochloric acid. 0.15 mol of hydrochloric acid a is added

C, 55 mol of hydr. chromium trioxide dissolved in x

Ιγ, β g formic acid 85r% · The reaction mixture was heated in a closed kettle _r 5 hours at 115 to 120 ° C. After cooling, 67 g of wet = 52 g of dry crystalline chromium are obtained

of a single product.

Claims (1)

P 5 B D II S T OF THE INVENTION 236 435 MM base-bti va. Process for the preparation of chromium complex (I) a) wherein one of the four X is -SO ^ H, and the remaining three are hydrogen, X chromací monoazo dye of the formula II wherein D is hydrogen one of the four X is -SO-H and the other three X are chrojako jsouV ^ ^J ^ mity chloride salts sulphate, alum, hydrous chromium trioxide in an aqueous medium, characterized in that the chromation is carried out with the addition of 0.05 to 0.3 mol of mineral acid, based on 0.1 mol of chromium salt, optionally with an addition of 0.01 to 0, 3 mol of formic acid.