DE89027C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

GREAT

'Dyes, varnishes, lacquers

. 0 O

It is well known that purpurine can be treated with reducing agents in alkaline Solution with ease replacing a hydroxyl group with hydrogen, and indeed succeeds so to xanthopurpurin.

When the Reduction. accomplished in very weakly alkaline, neutral or acidic solution is not xanthopurpurine, but quinizarin in a smooth manner. Simultaneously the ketone groups of the anthraquinone nucleus are also partially reduced with the formation of reduction products (leuco derivatives) quinizarin, which can easily be converted into the latter by oxidation. The reduction in acidic solution can, for. B. in glacial acetic acid or in concentrated sulfuric acid are executed. Zinc dust is expediently used as a reducing agent, however can also use other substances, such as. B. tin, aluminum, aluminum amalgam, tin chloride and so on.

The reduction of purpurin in glacial acetic acid solution by zinc dust proceeds very smoothly. This results in two different leuco derivatives of quinizarin, which are to be referred to as leucoquinizarin I and leucoquinizarin II. These can easily be distinguished from one another by the fact that leucoquinizarine I changes to quinizarine by oxidation much more easily than the other, which is particularly clear if one simply uses concentrated sulfuric acid as the oxidizing agent. By the latter I leucoquinizarine at ordinary temperatures slowly converted at 70 to 90 degrees in a few moments in quinizarin while leucoquinizarine II is about 120 to 130 oxidizes ⁰ to quinizarin only at a higher temperature. This behavior also permits the course of the reduction of purpurin to leucoquinizarine I and the further reduction of the latter to leucoquinizarine II in an excellent manner

to pursue.

Example I.

50 kg of dry, finely powdered purpurin are suspended in approx. 250 to 400 kg of glacial acetic acid, the mixture is heated to 70 to 80 ° and now approx. 25 kg of zinc dust with vigorous stirring entered in portions. The reduction proceeds rapidly with the development of heat, and is finished when the purpurin with the yellow color inherent to the reduction product has gone into solution. One filters thereupon from unchanged zinc dust and separates the reduction product from the filtrate by adding water. Leucoquinizarin is obtained by recrystallizing from acetone I pure in the form of golden-yellow, shiny leaves, which in hot acetone, alcohol, glacial acetic acid with a yellow and bluish color Fluorescence are easily soluble. the

Solution in concentrated sulfuric acid is yellow, and goes, as already mentioned, on standing slowly, very rapidly when heated, with evolution of sulphurous acid in quinizarine above. The solution in caustic soda is yellow and soon turns purple when exposed to air, by adding Oxidation to quinizarin takes place.

The elemental analysis showed the following values:

C: 65.11 and 65.08 pCt.
H: 3.95 and 3.90 pct.

If, in the above example, the amount of zinc dust is increased to about 50 kg and the reduction is continued until an isolated sample of the reduction product, when briefly heated with concentrated sulfuric acid to 80 to 90 °, no longer gives quinizarine, but remains unchanged, then it is obtained the leucoquinizarine II mentioned at the beginning, which is isolated in the manner described above. It crystallizes from acetone, ligroin, etc., in long, red-yellow needles with a melting point of 50 °. When heated with concentrated sulfuric acid to 130 ^° or higher, it changes to quinizarin. The yellow solution in sodium hydroxide solution also changes into the purple quinizarin solution due to the action of atmospheric oxygen, but more slowly than leucoquinizarin I.

The elemental analysis showed:

C : 69.32 and 69.05 pCt.
H: 4> 9 and 4.13 pCt.

The connection is therefore very likely identical to that of Liebermann (Ann. Vol. 212, p. 14) described quinizarinhydrur.

If it is only a question of making the quinizarin itself from purpurine, so it is of course not necessary in view of what has been said above, the two just described To subject leuco compounds to oxidation. One can as well use a mixture of both and therefore only need to drive the reduction so far, until no more purpurin can be detected.

Example II.

10 kg of purpurin are dissolved in approx. 200 kg of sulfuric acid. In the at-10 to-5 ⁰ cooled solution with vigorous stirring and by shall ensure the temperature remains DAF as low as possible, entered as long as zinc dust, to a worked-up sample no longer purpurin be demonstrated. This requires about 20 kg of zinc dust. The lower the temperature, the better the reduction. The melt is poured into ice water, the reduction product separating out in yellow flakes, which are filtered off, washed and dried. They consist of a mixture of the two leuco compounds of quinizarin described above.

Example III.

For the reduction of purpurin in neutral Solution, 10 kg of Purpurin are slurried in the finest possible dough form with 500 1 of water, Entered 20 to 25 kg of zinc dust and bring the mixture to the boil with constant stirring heated. The boiling is continued until keiri purpurin can be detected and a sample of the reaction product is in caustic soda and in concentrated sulfuric acid dissolves with a brownish yellow color. The whole then becomes a decomposition of what has been partially formed Zinc varnish and the still unchanged zinc dust are strongly acidified with hydrochloric acid, the Reduction product filtered off, washed and dried. The same is also an alternating one Mixture of the two leuco compounds of quinizarin.

Instead of the suspension of finely divided purpurin in Weakly alkaline solutions of purpurin can also be applied to water with the same results e.g. solutions in the just sufficient amount of soda, borax or similar Substances. The solution of purpurin in aqueous aluminum sulfate solution can also be used or a solution in alcohol etc. be used.

Similarly, other polyoxyanthraquinones which contain hydroxyl groups can also generally be used contained in purple division, are converted into less hydroxylated oxyanthraquinones. So you get z. B. by reduction of Hexaoxyanthraquinone or Alizarinhexacyanin in glacial acetic acid or concentrated sulfuric acid lightly leuco derivatives of alizarin pentacyanine, which can be transformed into the latter by oxidation. The reduction in glacial acetic acid solution takes place e.g. B. exactly the same way like that of purpurin. Here, too, two corresponding ones arise one after the other Leuco derivatives of alizarin pentacyanine. The first reduction product, the leucoquinizarin I. accordingly, it is extremely easily oxidizable: concentrated sulfuric acid already transforms it quickly in the cold in pentacyanine. Its isolation in a pure state is therefore with connected with great difficulties. The second reduction stage, corresponding to the Leukochinizariri II, is also more easily oxidized than the latter, but can be removed in the pure state represent, crystallized from glacial acetic acid in large brownish-yellow leaves or flat needles, which sometimes contain crystal acetic acid, and dissolves with concentrated sulfuric acid brownish yellow color. The solution in sodium hydroxide solution is orange-yellow and becomes when the

Claims (2)

Air very quickly turns blue due to oxidation. It does not matter whether you use hexaoxyanthraquinone or alizarinhexacyanine for reduction. Purpurin sulfonic acid, too, which is obtained by sulfurizing purpurin or by oxidation of the common alizarin sulfonic acid, is converted into leuco compounds of quinizarin sulfonic acid by reduction in neutral or acidic solution. Example IV. 100 kg of purpurin are obtained by heating with 20 kg of oleum of 20 pCt. Sulfurized the SO3 content to 100 °, poured the mixture obtained into 500 to 1000 liters of water and added. Zinc dust reduced at ordinary temperature. The resulting leuco compound respectively. the mixture of leuco compounds of quinizarine sulfonic acid is salted out and can be converted into quinizarine sulfonic acid by oxidation in an acidic or alkaline solution. Godfathers τ-claims ρ ρ odor: 1. Process for the conversion of those oxyanthraquinone derivatives which contain hydroxyl groups contained in purple setting (1, 2, 4), in leuco compounds of oxyanthraquinone derivatives, which contain the hydroxyl groups in the quinizarin position (1,4), consisting in the fact that the former are in neutral, weakly alkaline or acidic solution with suitable reducing agents treated. 2. The special embodiments of the under ι. claimed method using from a) Purpurin for the preparation of leuco derivatives of quinizarin, b) Hexaoxyanthraquinone and alizarinhexacyanine for the preparation of leuco derivatives of alizarin pentacyanine, c) Purpurinsulfonic acid for the preparation of leuco derivatives of quinizarinsulfonic acid.