CS254616B1 - Process for preparing unsymmetrical brown metal complex dyes - Google Patents

Abstract

A method for preparing 2:1 unsymmetrical brown metal complex dyes based on chromium complexes of constitution I by the action of a chromium complex of constitution II on azo dyes of constitution III, where Aj is always a group -SO,I1 or -NO2 and A2 -NO, or SO,H, in an alkaline medium containing ammonia and alkali carbonates.

Description

SUMMARY OF THE INVENTION The present invention provides a process for preparing brown unbalanced 2: 1 metal complex dyes based on chromium complexes of constitution I dyeing wool, silk and synthetic polyamide textile materials.

where

A 1 is -SO 2 H or -NO ₂

A ₂ is -NO ₂ or -SO 4 H

Hitherto known methods for the preparation of the above-mentioned metal-complex dyes of constitution I consist in simultaneous chromation of an equimolar mixture of starting azo dyes, the disadvantage of which is the production of a dye mixture containing besides the desired 2:

It has now been found that the above-mentioned type of constitutional chromite complexes can be efficiently and without these drawbacks prepared from commonly produced 1: 1 constitutional chromite complexes

by their action on the azo dyes of Constitution III

wherein A 1, A ₂ are substituents as previously defined in an alkaline or neutral reaction medium at a temperature of 80 to 100 ° C.

The process for the preparation of unsymmetrical constitutional chromium complexes I according to the invention is carried out by adding a neutral or weakly alkaline suspension of 1: 1 constitutional chromium complex II to an ammoniacal solution of an equimolar amount of azo dye III in the presence of alkaline carbonates at said temperature.

The complexing reaction according to the invention makes it possible to work at very high initial concentrations of the input components II and III without the need for isolation of product I.

I is characterized by its high solubility with excellent coloring properties.

The advantage of the process of preparing 2: 1 asymmetric chromium complexes of the constitution I according to the invention is the possibility of highly productive utilization of the production equipment and of the available raw material base with minimum energy and auxiliary consumption. Another advantage is the possibility of a waste-free and non-insulated way of conducting the technological process.

The invention is further illustrated by the following non-limiting examples.

Example 1

1,250 liters of water at 50-60 ° C and 1 mole of constitutional dye are introduced into the vat with stirring

the acidity of the suspension is blunted by adding 50 kg of sodium carbonate to a pH of 7 to 8 and the mixture is heated to a temperature of 80 to 90 ° C.

The stirred reactor was charged with 1000 liters of water 50 to 60 ° C warm, in which 45 kg of sodium carbonate was dissolved and 1 mol of azo dye was added to the solution.

which is dissolved by the addition of ca 75 liters of a 25% ammonia solution so that the pH of the solution is between 8.5 and 9. The reactor contents are heated to a temperature of 85 to 90 Ca and a 1: 1 chromium complex suspension is gradually introduced into the reactor. After 1 hour heat exposure, when the starting components are reacted quantitatively, the reaction mixture is made up to the desired coloristic strength with sodium sulfate to reduce the dustiness of the final product and dried directly in a spray drier.

Example2

The preparation procedure is identical to Example 1, except that the constitution azo dye is used in place of Example 1 in the azo dye.

Claims (1)

Process for the preparation of unsymmetrical brown metal-complex dyes based on chromium complexes of the constitution I A, is the group -SO ₂ H or -NO ₂ A ₂ is the group -NO ₂ or -SO ₂ H, characterized by the fact that a 1: 1 chromium complex of constitution II is reacted II and the azo dyes of Constitution III ^and 2 III wherein A 1 and A ₂ are as defined above, in an alkaline medium containing ammonia and alkali carbonates at a temperature of 80 to 100 ° C.