DE1886C - Process for the preparation of blue dyes from dimethylaniline and other tertiary aromatic monamines - Google Patents

Description

1877.

- great

. BADISCHE ANILINE- and SODA-FACTORY in MANNHEIM,

Process for the preparation of blue dyes from dimethylaniline and other tertiary ones

aromatic monamines.

Patented in German, Reiche from December 15, 1877 -ab. '■''''■;'. ■ '■ ■ ■'! ";'

Our invention aims at the representation of blue dyes, which differ from tertiary aromatic monamines and in particular from dimethylaniline.

To this end, we subject the para-amido substitution products of the tertiary monamines of a reaction, which essentially coincides with that which occurred a few years ago Time Charles Lauth for the production of violet dyes from the paradiamidobenzene and whose homologues have applied. (In. D. D. formerly Ges. 1876, pag. 1035; Bull. Soc. Chim. 1-876 II. Sem. p. 422.)

Lauth's reaction consists in making acidic and dilute solutions of aromatic Diamines are treated with hydrogen sulfide and oxidizing agents at the same time. These Reaction, however, has not yet been able to achieve any practical use, because on the one hand the production of such violet dyes does not meet any technical need, and on the other hand, it depends on the representation of paradiamidobenzene or its homologues is. It is well known that the diamines mentioned can only be obtained by expensive detours. Lauth has also already stated that the violet ones produced by his method Dyes of substitution by methyl etc. are capable and by the same in blue or green dyes pass over.

In view of the aforementioned difficulty in producing Lauth's dyes economically, much less can one think of them as the starting point of the presentation to choose from substitution derivatives.

In the same way now that dimethylaniline and other tertiary monamines permit the direct and practically advantageous preparation of dyes which previously only We use the detour of substitution from which rosomilin could be obtained of dimethylaniline and some other tertiary monamines, in order to be more direct and economical Way to produce blue dyes from the same.

In the following we first describe the representation of a blue dye the dimethylaniline. It breaks down into three operations:

First operation: preparation of nitroso-dimethylaniline.

Second operation: reduction of the same to amido-dimethylaniline.

Third operation: conversion of the latter into the blue dye.

First operation.

To prepare the nitroso-dimethylaniline, we prepare a cold solution of
10 kg dimethylaniline in
30 kg of concentrated hydrochloric acid and
200 l of water
and let in it a resolution of

5.7 kg of pure sodium nitrite (1 Molecul) in 200 l of water

run in while stirring continuously for four to five hours.

The mixture turns yellow and contains crystals and a solution of the hydrochloric acid nitroso-dimethylaniline.

Instead of the above-mentioned pure sodium nitrite, the equivalent amount of is of course free nitrous acid or other compounds thereof can be used.

Second operation.

To reduce the nitroso - dimethylaniline produced as above to amido - dimethylaniline you can see the usual reduction methods by finely divided metals, such as. B. Use iron, tin or zinc. We prefer, however, to add the hydrogen sulfide apply for this purpose and proceed as follows:

The solution of hydrochloric acid nitroso-dimethylaniline obtained as described above is in a closed, with mechanical agitator and extraction device for the excess Hydrogen sulphide provided wood tanks with

500 1 water and

50 kg of concentrated hydrochloric acid
and then a stream of hydrogen sulfide gas passed into it until the yellow color of the solution has completely disappeared.

Claims (1)

During the. Reduction, the liquid becomes temporarily red, at last colorless and covered with a bluish foam. The liöslmg contains this ^{Städiumsalzs'aures;!} Amido Dimethylanilirit * lind already 'a part of the new sulfur dye ^in: Forrn a colorless compound. Instead of the gaseous hydrogen sulfide can, of course, be in the same Way of sulphurous sodium, of sulphurous ammonium or use other sulfur metals decomposable by hydrochloric acid, which gradually adding to the acidic liquid. Third operation. The formation of the blue dye requires the addition of an oxidizing agent to that obtained from the second operation and with Colorless reducing liquid saturated with hydrogen sulfide. Be for this purpose 200 1 of a ferric chloride solution sp. G. 1.07
or so much of it is slowly added until the odor of the hydrogen sulfide has disappeared and the oxidizing agent is present in a slight excess. Instead of iron chloride, an equivalent amount of potassium dichromate or a similar oxidizing agent can be used; however, we prefer the cheap ferric chloride. Instead of the oxidizing agent as indicated above to act on the hydrogen sulfide-containing solution of the amido-dimethylaniline one can also reverse the sequence of operations. The amido-dimethylaniline is treated first with the oxidizing agent, and then leads the resulting, colorless and unstable oxidizing product in a strongly acidic solution by adding hydrogen sulfide to the blue dye. In this case it is necessary for oxidation and hydrogen sulphide to occur very quickly to allow the hydrogen sulphide to follow one another only to the point where it prevails slightly to feed. This method is therefore more difficult to implement than the former. We carry out the separation of the dye in the following way. The mixture is saturated with common salt and so much an aqueous zinc chloride solution is added that the dye appears completely precipitated. Then, it is filtered and the filter on the _r remain d.en · .NiederschlageVdurehiitccessives treatment with ^ the ^water; '.biau «y slightly soluble dye" ■ withdrawn. - "... J' ^ '· ■■ : fc; · ■ ·. "" ■■ ", '' ... .. ■ .-. The filtered 'solutions, of the same are of saturated with koih salt and made from them by adding zinc chloride, filtering, Pressing and drying the dye obtained in the form of its zinc chloride compound. In this form the dye is easily soluble in water and is for technical use suitable; we therefore prefer the zinc chloride to other metal salts and precipitants, which in similarly allow the conversion of the dye into a commercial form, restrict however, we do not rely on the exclusive use of it. The preparation of the amido-dimethylaniline can, as is known, likewise by reduction of the mononitro-dimethylaniline take place and also this base is formed, if one a diazo compound in a molecular ratio with dimethylaniline to an azo compound united and then treated the latter with reducing agendas. For the purpose of the factory production of our blue dye, however, we hold the passage through the nitroso-dimethylaniline described above for the most advantageous Path. In addition to dimethylaniline, the same process can be used to make dimethyl orthotoluidine, Diethylaniline, methyl- and ethyl-diphenylamine and analogous tertiary monamines represent blue dyes, which, however, neither by cheapness nor by their coloring properties have a process before the dyes formed from the dimethylaniline. The proportions given above provide a practically satisfactory one Result, however, can vary within wide limits, which is why we do not address each other keep them exclusively bound. Patent claim: The method described above for displaying bluer Dyes from dimethylaniline and other tertiary monamines by conversion thereof into their amido substitution derivatives and treatment of the latter with hydrogen sulfide and oxidants in cold, dilute, and acidic solutions. ;