DE602338C - Process for the production of dyes - Google Patents

Description

Condensation products from sulfoacetic acid with phenols have not yet been obtained been.

It has now been found that by j. Heating an aqueous solution of sulfoacetic acid with a phenol with a free para position to about 100 ° well-defined and well-crystallized dyes obtained by condensation of apparently two molecules Phenol with a molecule of acid and leakage of water are formed.

The reaction of phenols with sulfoacetic acid-containing acetic anhydride is true known (see reports of the German Chemical Society 35 [1922], page 1893, note 5); but since the sulfoacetic acid is only used here as a condensing agent or as a catalyst works, the products obtained do not contain any sulfur in the molecule and differ significantly from the

Dyes, the production of which is the subject of the present process.

The constitution of these dyes was not determined, but their percentage composition and the extensive analog

gie with the dyes of the phthaleins group justifies the assumption that one is dealing with dyes of a constitution similar to that of the phthaleins, which but a coloring that is important to the molecule

^ ⁰ contains sulfo group which gives properties. The simplest dye obtained with phenol probably has the following constitution:

-OH

= 0

- SCLH

The concentration of sulfoacetic acid, the temperature and the duration of the heating are determined by the nature of the phenol used. Generally it is from Advantage, in aqueous solution at about 100 ° and with a large excess of sulfoacetic acid to work and stop the process before the reaction is complete, to avoid the formation of by-products and avoid tarry fabrics.

In this way, well-defined and well-crystallized dyes with phenol, Orthocresol, resorcinol and pyrogallol have been obtained. Meanwhile, the yields are the use of orthocresol and even more so with phenol very bad. These two final dyes are therefore only cited to ensure the general validity of the reaction to prove.

Example ι

The mixture is heated at a temperature between 95 and 100 ° 252 parts of pyrogallol with 356 parts of a 79 ° / ₀ strength aqueous solution of sulfoacetic acid. The liquid slowly turns wine-red, and small crystals of a dye gradually precipitate.

The reaction is stopped after 70 hours. One dilutes with water, sucks removes the dye and, if necessary, cleans it by dissolving it in sodium bisulfite with the it forms a colorless and nicely crystallized compound. By adding hydrochloric acid the dyestuff is obtained in high purity in the form of a bisulfite solution crystalline brown powder that turns red-purple in soda and deep blue in alkalis solves. There are blue-black dyeings of great authenticity on chrome-stained wool.

Example 2

The mixture is heated to 95 to 71 parts of resorcinol with 238 parts of an 80% aqueous solution of sulfoacetic acid. The mass slowly turns deep red. After an hour After heating, the reaction product is diluted with 3 parts by volume of water and shaken with the same amount of ether. The dye gradually separates from the ether in small brown, shiny metallic crystals, which, as described above, over their bisulfite compound can be purified.

The dye thus obtained appears in brown, purple shimmering needles, which in Alkalis with the color and strong green fluorescence of ordinary fluorescein are soluble. The dye can be brominated like this in acetic acid solution and provides a dye that crystallizes in fine red needles and is found on silk and wool Gives colorations comparable to those obtained with eosin.

In the two examples above, is far more than the theoretical amount of Sulfoacetic acid has been used. This excess sulfoacetic acid is recovered easily back by the fact that the aqueous solutions after separation of the dye precipitates with chlorobarium with the addition of ammonia.

Claims (1)

Claim: Process for the preparation of dyes, characterized in that one Sulfoacetic acid condensed in aqueous solution with phenols with a free para position.