SU42646A1 - The method of obtaining alizarin - Google Patents

Description

It is known that, during oxidation treatment in alkaline solutions, an anthraquinone in an autoclave at a temperature of 180–200 ° in the presence of sodium sulfite turns into alizarin for 3–4 days (germ. Pat. No. 241806). The role of sulfite in this method has not been elucidated, although it is so significant that the specified reaction almost does not take place without sulfite.

Subsequently, instead of sulfite, other substances were used, such as the sodium salt of anthraquinone p-sulfonic acid (germ. Pat. No. 245987), as well as salts of organic sulfonic acids, hydrosulfuric acid, thiosulfuric and polythionic acids, and likewise sulfides capable of an alkaline process. turn into sulfites (germ. Pat. No. 251236).

Finally, it is also known that the considered process of oxidation of anthraquinone to alizarin improves from the introduction of lime into the recipe (germ. Pat. No. 249368, sov pat. No. 14118; cf. also germ. Pat. No. 292247).

Assigning the role of inducer between nitrate (actor) and anthraquinone (acceptor) to sulfite and similar compounds, we found that the formation of alizarin during the direct oxidation of anthraquinone can be carried out under optimal conditions in terms of reaction rate, yield yield and purity of the product if another suitable catalyst is introduced into the system of the usual components of the conjugate reaction. As such, formaldehyde and benzaldehyde, capable of being oxidized to the corresponding acids, salts and vanadium compounds, complex compounds of copper and its various salts, for example, nitric acid, sulfuric acid, etc., have proven suitable.

In the presence of catalysts, the reaction proceeds quickly and easily, for example, the mixture is already in the test tube with the addition of trace amounts of vanadium chloride and with heating it develops a strong reduction of nitrate to ammonia, etc. The autoclave process, usually taking place in laboratory conditions of 12-15 hours and accompanied by the release of alizarin 75-77%, in the presence of copper sulphate, proceeds to the end in 5 hours with the release of alizarin to 95-96% with outstanding purity of the product (alizarin bluish), and the copper sulphate is reduced to m the metallic copper in the form of minute powder.

Example:

Nngrahinona .... 41.6 g (1.5 mol)

Caustic soda .... SO g

Vody300-50 SN

Sodium sulfite. .15-20 g

Saltpetre12-75g

Lime 11.0 g

Catalyst is optionally one of the following products;

Benzaldehyde2,5 ate

or

Vanadium chloride .... 0.2 g Copper sulphate .... 1.0, and so on.

This mixture is heated in an autoclave with a stirrer for 5 hours at a temperature of 190-200 °, and the pressure reaches 24-25 atm., And after the reaction (during cooling of the autoclave) the residual pressure is about 2-

3 atm Reaction processing

the mass is accomplished in the usual way.

The subject matter of the invention.

The method of producing alizarin by the oxidative alkaline melting of anthraquinone in the presence of sulfur salts of sulfuric acids or of sulfonic acids or sulfides, characterized in that the fusion is carried out with an addition of aldehydes, or salts of vanadium compounds, or salts of copper, or its complex compounds.