CS236436B1 - 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 where one X = -NO2 and the other X = H one X -SO^H and the other Y with H by chromating a monoazo dye in the presence of formic acid and mineral acid.

Description

The complex of general formula I is an intermediate in the production of dyes suitable for dyeing wool, silk, polyurethane or polyamide fibers, or their mixtures, from a weakly acidic to neutral bath in orange to red shades with high fastness, but it can also be used for other dyeing purposes.

Chromium complex I is prepared by the action of chromium salts on the starting monoazo dye in an aqueous medium at a temperature above 100°C.

The disadvantage of this procedure is that to achieve a chromatically uniform product, the reaction mixture must be heated for a long time and the chromization does not occur quantitatively.

-2236 436

The disadvantages of the current state of the art are eliminated by the method of preparing the amazing complex of formula I

where either X « -K0 ₂ ^and the other X = H one Y = -SO^H and the other Y =H, chromizing the monoazo dye of formula II

where one X => -N0 ₂ and the other X = H, one Y . -SO^H and the other Y = H, with the above compounds in an aqueous medium according to the invention, by chromating with the addition of 0.05 to 0.3 mol of formic acid and 0.05 to 0.3 mol of mineral acid, based on 0.1 mol of chromium compound. Preferably, chloride, sulfate, chromic hydrogen peroxide can be used for chromating.

Example 1

To 0.1 mol of the coupling suspension of the monoazo dye 4-nitro-2-aminophenyl < _- 1(4'-sulfophenyl)~3-methyl-5-pyrazolone with a volume of

000 is added 65 g of chromite potassium alum (0.13 mol KCr(SO^) ₂ 12 H ₂ 0).4.1 g of formic acid 85% (« 12 g of formic acid 100% » 0.2(Ζήο1() and 0.065 mol of sulfuric acid. The reaction mixture is heated for 6 hours at 12513Ó*°C» After cooling, 74 g of paste is isolated » 49 g of dry matter r .

236,436 of chromatographically pure 1 with 1 chromium complex.

Example 2

To 0.1 mol of a coupling suspension of the monoazo dye 4,8,5-nitro• -2-aminophenol -1(4’-sulfophenyl)-5-methyl-5-pyrazolone "with a volume of 1,000 ml and a pH value of 2-5, 0.06 mol of hydrated chromium trioxide (0.12 mol Cr) dissolved in 15 S of 85% formic acid (= 11.05 g of 100% formic acid ». 0.24 mol) is added, kept at 85 °C for 2 hours, acidified with 0.56 mol of hydrochloric acid and heated in a closed kettle for 4 hours at 120 to 125 °C. After cooling, 64 g of paste with 49 g of dry matter of chromatographically pure product is isolated.

Example 5

To 0.1 mol of a 1,000 ml coupling suspension of the monoazo dye 5-Citro-2-aminophenol-1(5 ^, -sulfophenyl)-5-methyl-5-pyrazolone and adjusted to pH 2-5, 0.06 mol of Cr ₂ O^ hydrate dissolved in 19.5 g of 85% formic acid (=16.6 g 100% = 0.56 mol) is added and heated for 2 hours at 80 to 90 °C.

Then it is acidified with 0.56 mol of hydrochloric acid and heated in a closed kettle for 4 hours at 125° C. After cooling, 73 g of paste with 45 g of dry matter of a chromatographically uniform 1:1 chromium complex is isolated.

Claims (1)

FOR THE INVENTION 236 436 m <meaxob <iv £ wt. A process for the preparation of a chromium complex of the formula wherein one ΣΣ-Νθ | and the second X = H one Y »-SO ^ and the other Y = H, by chromating the monoazo dyes of the general formula j / where one X = -NO ^ and the second X = H and one Y · -SO ^H and the other Y «H by chromite compounds in an aqueous medium, characterized in that the astonishing is carried out with the addition of 0.05 to 0.3 mol of formic acid and 0.05 to 0.3 mol of mineral acid, based on 0.1 mol of the compound,