SU31525A1 - The method of obtaining sulfur dyes - Google Patents

Description

The usual method of producing sulfur dyes from aromatic nitro compounds (dinitrophenol), nitroamino compounds, indophenolate, etc., is that the mixture of organic matter with the polysulfide solution is cooked for a prescribed time at a certain temperature and concentration.

In the process of cooking under the action of polysulfide, the original organic matter is reduced by the equation: RNOa + NazSx + HgO RNH2 + Na2S2O3 +

+ Sx -2

The sulfur released from the polysulfide during the reduction process enters the aromatic core. In this case, the formation of a thiacin core and a number of unexplored condensation reactions, the formation of quinoid groups, etc., take place.

It has been established that the best results on the yields and quality of the dye, as well as on the reaction rate, can be achieved if oxidants are introduced into the reaction mass, such as: 1) sodium nitrite, 2) air oxygen, 3) aromatic nitrosulfonic acids, not containing OH groups (for example: methanitrobenzene sulfonic acid), 4) potassium persulfate and the like

similar substances, which, after their reduction, are converted into products that are soluble in a weakly alkaline medium (the use of oxidizing agents containing halogen is excluded, since the latter acts destructively on most sulfur dyes).

The cooking process in the proposed method is divided into two stages: reducing and oxidizing. For the oxidation stage to succeed, the reduction of organic matter must be completed.

The end of the first stage is determined by the disappearance of the unreacted starting product. For this purpose, different qualitative reactions can be applied, depending on the applied organic matter source. For example, if the starting material is sodium dinitrophenol t, discoloration of an orange sample on a filter paper under the influence of lead acetate indicates the presence of an unreacted product. In addition, it is possible to quantify the percentage of the hyposulphite formed in the process of reduction, and accordingly with its increase, to control the process of organic matter reduction. (The method of determination - see the journal "Mnilino-krasoch" and industry, 1931 № 11-12 p. 23).

At the end of the reduction, a melt is obtained which is a visible solution of inorganic salts mixed with organic matter (depending on the starting material, the reaction product is dissolved or suspended in an aqueous solution). With continued stirring and heating until boiling, an oxidizing agent is gradually introduced into this melt in an aqueous solution (for example: nitrite, nitrobenzenesulfonic acid), or in the form of a thin gas stream (oxygen of air).

The oxidizing agent must be introduced in small portions, gradually, otherwise the reaction proceeds too rapidly with foaming and release of the reaction mass from the apparatus.

With the gradual introduction of an oxidizing agent

in the process of cooking quickly ends

sulphurization of organic matter and

a dye with a good yield is formed

and shade.

Example 1. Preparation of sulfur black dye from dinitrophenolate 1. 2. 4.

Dinitrophenol obtained from 110 parts of dinitrochlorobenzene is combined with polysulfide, obtained from 60 parts of IOOVo NajS, and 70 parts of sulfur, at a temperature of 105-107 and bales with stirring until the unreacted nitro compound disappears.

At the end of the reduction (qualitative reaction is given above), air is gradually passed into the melt with continued stirring and boiling at a temperature not lower than 105-107 °, for b-8 hours, until the formation of the coloring matter is complete. The dye is drained in the form of a paste, either; it is isolated as usual and filtered on a filter press.

Example 2. Getting sulfurous, direct dye from dinitroxydiphenylamine.

320 tons of dinitrooxiphenylamine are combined with polysulfide from 203 kg lOOVo MaaS, 42 kg 100 ° / NaOH and 350 kg sulfur, about 1000 liters, temperature-107 °.

Cooking is carried out at temperatures up to 112-114 ° until both nitro groups are completely reduced (control of the amount of hyposulphite formed).

At the end of the reduction, 133 tons of technical nitrite in a solution of 200-250 liters of water are gradually added to avoid rapid foaming, and after the addition is complete, 8–8 hours are refluxed.

The dye is recovered filtered and dried as usual.

The subject matter of the invention.

The method of producing sulfur dyes from compounds reduced by sulfurous sodium or polysulfides, such as nitro compounds, indophenols or the like, by fusing with alkali metal polysulfides, characterized in that the fusion process is carried out in two stages, of which in the first under normal conditions, the process is brought only to complete recovery of the raw materials without completing the formation of dye. In the second, the fusion is continued with addition to the melt without diluting its oxidizing substances, for example, nitrites, the non-hydroxyl groups of the nitro compounds of potassium persulfate, air blown through the melt or the like and after the end of the fusion are processed by the melt by conventional methods.