DE610760C - Process for the preparation of azo dyes - Google Patents

Description

Process for the preparation of azo dyes the subject of the main patent 60 ¢ 57 & is a process for the preparation of azo dyes using from [-Nitro-i, 3-, diaminoben20l, of which one amino group is converted into the diazo group has been. This diazo compound is acidic, neutral with any components or alkaline medium combined to form azo dyes, which are used for coloring animal Fiber, leather, acetyl cellulose, etc. are suitable.

It has now been found that there are also very good ones, especially for dyeing of leather and acetate silk receives suitable dyes if one uses them Substitution products of the q.-nitro-i, 3-, diaminobenzene, which have no further negative Substituents such as chlorine containing nitro or sulfonic acid groups are monodiazotized and couples with any components.

EXAMPLE I 1 6.7 parts of i-methyl-2,4-diamino-5-nitrobenzene are dissolved with 25 parts of hydrochloric acid (20 ° B6) and 100 parts of water in the heat. The by running the solution in a. Mixture of ice and water obtained - suspension is monodiazotized at o'C by adding a solution of 6.9 parts of sodium nitrite. As soon as the reaction to nitrous acid has disappeared, a hydrochloric acid solution of 14.9 doughs of diethylaminobenzene is added and a sodium acetate solution is gradually allowed to run in until the hydrochloric acid reaction disappears. After the coupling has ended, it is acidified with hydrochloric acid, the dye is separated from the liquid, for purification it is again stirred with water and excess sodium carbonate and again separated off. He dyes acetate silk from the suspension in real orange tones.

If the diethylaminobenzene is replaced by 13.7 parts of i-1VIethy1-3-amino-q.-methoxybenzene, an acetate silk also orange, but a little red-coloring dye, is obtained. Example 2 = -The i-methoxy-2, q.-diamino-5 nitrobenzene is used, which is obtainable by nitrating the i-methoxy-2,4-diaetaminobenzene and splitting off the acetyl groups. It forms orange-colored crystals with a melting point of i66 ° C. 36.6 parts of this i-methoxy-2, q.-dia.mino-5-nitrobenzene are dissolved warmly in parts of concentrated hydrochloric acid and parts of water and poured slowly into a mixture brought to the separation of ice and water in fine form. It is then diazotized at o'C by adding a solution of 13.8 parts of sodium nitrite. The diazo compound is allowed to run into a solution of the monoazo dye made from 31.9 parts of diazotized i-amino-8-oxynaphthalene-3, 6-disulfonic acid and ii parts of resorcinol, which is kept alkaline by sodium hydroxide solution. After the coupling is complete, it is separated off by adding salt and worked up in the usual white. The resulting triazo dye dyes leather from acidic liquor in deep brown shades which are somewhat redder than the shades obtained on leather with the corresponding dye from 1,3-diamino-4-nitrobenzene.

It has already been proposed (see British patent specification 266 388) to produce monodiazo compounds from substituted m-diamine of the benzene series. According to this process, the diamine is obtained by treatment with, for example, chlorosulfonic acid converted into the corresponding disulfamic acid. When treating with nitrous Acid, a sulfuric acid group is rinsed off and the amino group thus released diazotized.

In contrast, according to the present process, the substituted Nitro-m-diamine immediately diazotized. So there is the intermediate formation of sulfamic acidxi path.

Claims (1)

PATENT CLAIM: Process for the preparation of azo dyes according to patent 604378, consisting therein; that instead of the q.-nitro-i, 3-diaminobenzene mentioned there, its substitution products, which contain no further negative substituents such as Cl, NO 2, S 03 H, are monodiazotized and coupled with any components.