SU48932A1 - The method of obtaining azo dyes - Google Patents

Description

The subject of the present invention is a process for the preparation of azo dyes having a number of valuable properties. These dyes are evenly evolve, give durable varnishes with mordants and are suitable for dyeing animal fibers, both directly and through mordants, then their colors drastically change color from subsequent processing with chromium, chromium fluoride, aluminum alum.

The proposed method consists in the fact that its amino-terephthalic acid or any of its dialkyl ester or its nitro-amino-terephthalic (2-amino-5-nitro-1: 4-benzene-dicarboxylic) acid ate its esters diazotized and the resulting diazo compounds combine with conventional azo compounds.

Compared with similar dyes derived from anthranilic acid, the second carboxyl group in the derivatives of amino terephthalic acid increases color and is a hypsochromic group; the esterification of carboxyl groups also increases the chromaticity, and the introduction of the nitro group deepens the chromaticity.

Example 1.1 parts of amino terephthalic acid is dissolved per bale in b.hr. HC1 spd. at. 1.19 and 20 parts of water. The solution is rapidly cooled; the amine salt precipitates in small crystals. To a solution of the amine salt is added dropwise at 0 °

with stirring, a solution of 0.42 parts of NaNOa in 3 parts of water and continue stirring for another V2 hours. The resulting milky white liquid is then added dropwise with i.iipH vigorously stirring and a temperature of about -5 ° to the azo-component.

Example 2. 1 part of dimethyl ester of amino terephthalic acid is stirred at a temperature of 0-5 ° C for 4 hours. HC1 sp. at. 1.1 ° and 7 parts of water and a mixture of 0.35 parts of NaNOg in 4 parts of water is added dropwise at 0 ° C to the resulting mixture while stirring. After the addition of nitrate, stirring is continued for another half hour and the resulting clear diazo solution is added dropwise and, with stirring, to the solution of the azo-component (at a temperature O).

Example 3. 0.5 part of nitro-amino-terephthalic acid is dissolved per bale in 3 parts of water. The solution is rapidly cooled with ice and 2 hours of HC1 are added to it (sp. In. 1.19). Then, with vigorous stirring, a solution of 0.17 parts of NaNOa is immediately poured into 2 parts of water at a temperature of 0 °. Stirring is continued for another V2 hour at 0 ° and the resulting milky white liquid (stirred up diazo) is added dropwise and, with vigorous stirring, to the azo-component (temperature O-5 °).

By the method described above, the following azo dyes can be obtained:

subject matter of the invention.

A method of producing azo dyes, characterized in that amino terephthalic acid or a dialkyl ester of its or 2-amino 5-nitro-1: 4-benzene dicrabonic acid (nitro amino terephthalic) or its esters is diazotized and the resulting diazo compounds with usual azo compounds are combined .