Potassium Anthraquinone--sulfonate

It is necessary to provide an efficient stirrer driven by a powerful motor. The yields reported were obtained using a Hershberg Chromel wire stirrer (Org. Syn. 17, 31) with other stirrers the yields were lower by about 10 per cent. 

The recovered material contains mercury and other impurities and melts at 265-275°. When this is used as such in a second run, there is considerably more disulfonation than with pure anthraquinone. 

Under the conditions specified very little disulfonation occurs, so that the crystallizing mixture may be allowed to cool to 25° without danger of contamination of the product with disulfonates. When recovered anthraquinone is employed, it is advisable to collect the product when the mixture has cooled to 60°, for the disulfonates present in this case are then retained in the mother liquor. The solubility of the 1,5- and 1,8-disulfonates increases more rapidly with increasing temperature than that of the a-monosulfonate. 

The 57-g. yield refers to the experiment in which 53 g. of starting material was recovered the percentage yield improves with increase in the amount of anthraquinone recovered. 

The purity of the product may be checked by converting a sample to a-chloroanthraquinone (p. 15) and taking the 

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Fig. 7-7. Flow diagram manufacture of potassium anthraquinone sulfonate.

The conditions adopted in this procedure favor the production of a-monosulfonate in a state of high purity at the expense of a high conversion of anthraquinone. A better conversion can be achieved by conducting the sulfonation at a higher temperature, or by using more oleum, but in either case there is a considerable increase in the amount of disulfonic acids formed. The extent of /3-sulfonation is not influenced greatly by the temperature, but is dependent chiefly on the amount of mercuric salt present in the solution. The amount specified corresponds approximately to the limit of solubility of the salt in the acid employed, and very little of the /3-acid is formed. As the potassium /S-sulfonate is more soluble than the a-salt, traces of this isomer are easily eliminated by crystallization. 

Methylaminoanthraquinone has been prepared from 1-chloro-, 1-bromo-, and 1-nitroanthraquinone by treatment with alcoholic methylamine under pressure from 1-methoxy- and 1-phenoxyanthraquinone with methylamine in pyridine solution at 150° from potassium anthraquinone-1-sulfonate with aqueous methylamine at 150-160° from 1-aminoanthraquinone by treatment with formaldehyde, or methyl alcohol in sulfuric acid or oleum and by hydrolysis of />-toluenesulfonyl-methylaminoanthraquinone with sulfuric acid. ... 

Chlorination. a-Chloroanthraquinone is obtainable in almost quantitative yield by a procedure originated by UUmann and Ochsner and perfected as an Organic Synthe.ses preparation. A solution of potassium anthraquinone-a-sulfonate and... 

Aminoanthraquinone 355h Potassium anthraquinone-1-sulfonate (60 g) is heated with 24% ammonia solution (120 g) and sodium /w-nitrobenzenesulfonate (21 g) in a stirring autoclave up to 170-175° during 4 h and then kept at this temperature for a further 12 h (pressure ca. 25 atm). After cooling, the precipitate is filtered off, sucked dry, washed with a little hot water, boiled with acidified (HC1) water (300 ml), filtered off again, washed with hot water, and dried at 90°. This gives the technically pure product, m.p. 238°, in about 95% yield (39 g). Recrystallization from xylene affords a 75% yield of pure 1-aminoanthraquinone,... 

Procedure In a small dry flask provided with a reflux condenser (ground-glass joint) 1 g of potassium anthraquinone-2-sulfonate (well dried). 

Anthraquinone-l,5-disulfonic acid [117-14-6] (44), and anthraquinone-1, 8-disulfonic acid [82-48-4] (45) are produced from anthraquinone by disulfonation in oleum a higher concentration of SO than that used for 1-sulfonic acid is employed in the presence of mercury catalyst (64,65). After completion of sulfonation, 1,5-disulfonic acid is precipitated by addition of dilute sulfuric acid and separated. After clarification with charcoal, 1,5-disulfonic acid is precipitated as the sodium salt by addition of sodium chloride. The 1,8-disulfonic acid is isolated as the potassium salt from the sulfuric acid mother hquor by addition of potassium chloride solution. 

A 2-1. three-necked flask fitted with a stirrer (Notes 1 and 2), condenser, and dropping funnel (Note 3) is mounted in the hood, and in it are placed 20 g. (0.061 mole) of potassium anthra-quinone-a-sulfonate (p. 72), 500 cc. of water, and 85 cc. (1 mole) of concentrated hydrochloric acid. The solution is heated to boiling and stirred, while a solution of 20 g. (0.19 mole) of sodium chlorate (Note 4) in 100 cc. of water is added dropwise over a period of three hours (Note 5). The mixture is refluxed very slowly for an additional hour before the precipitated a-chloro-anthraquinone is collected by suction filtration and washed free from acid with hot water (about 350 cc.). After drying in vacuo at ioo°, the bright yellow product melts at 158-160° (corr.) and weighs 14.6-14.7 g. (97-98 per cent of the theoretical amount) (Notes 6 and 7). 

Sulfonation of anthraquinone to form the 1-sulfonic acid is achieved at approximately 120°C with 20% oleum in the presence of mercury or a mercury salt as a catalyst [2], Without this catalyst, the reaction produces the 2-sulfonic acid. Exchange with aqueous ammonia (30%) at about 175°C under pressure converts the potassium salt of 1-sulfonic acid to 1-aminoanthraquinone in 70 to 80% yield. To avoid sulfite formation, the reaction is performed in the presence of an oxidant, such as m-nitrobenzosulfonic acid, which destroys sulfite. 

As described, other nucleophilic reactions in the anthraquinone series also involve the production of anion-radicals. These reactions are as follows Hydroxylation of 9,10-anthraquinone-2-sulfonic acid (Fomin and Gurdzhiyan 1978) hydroxylation, alkoxylation, and cyanation in the homoaromatic ring of 9,10-anthraquinone condensed with 2,1,5-oxadiazole ring at positions 1 and 2 (Gorelik and Puchkova 1969). These studies suggest that one-electron reduction of quinone proceeds in parallel to the main nucleophilic reaction. The concentration of anthraquinone-2-sulfonate anion-radicals, for example, becomes independent of the duration time of the reaction with an alkali hydroxide, and the total yield of the anion-radicals does not exceed 10%. Inhibitors (oxygen, potassium ferricyanide) prevent formation of anion-radicals, and the yield of 2-hydroxyanthraquinone even increases somewhat. In this case, the anion-radical pathway is not the main one. The same conclusion is made in the case of oxadiazoloanthraquinone. 

The sulfo group in anthraquinone-I-sulfonic acid is replaceable, not only by amino and substituted amino groups, but still more easily by halogen. Thus, 1-chloroanthraquinone is formed in quantitative yield by treating the potassium sulfonate in boiling hydrochloric acid with sodium chlorate. The product is completely pure. The 2-sulfonic acid also undergoes this reaction, but much more slowly. 

A solution of 2 g of sodium anthraquinone-2-sulfonate and 15 g of sodium hydrosulfite in 100 mL of a 20% aqueous solution of potassium hydroxide affords a blood-red solution of the diradical dianion ... 

Hie above three isolation procedures can usually be conducted in such a way as to effect simultaneous purification from undesired by-product isomers. Thus, with the first method (dilution with water) the pure para isomer of tohienesulfonie acid is obtained since the ortho isomer is soluble likewise, the 1,5- and l, isulfonates (d anthraquinone are separated by taking advantage of different solubilities in sulfuric acid. When the second procedure is applied to the isolation of anthraquinone-l-sulfonate as the potassium salt, filtration at 85°C ensures removal of the 1,5-disulfonate in the aqueous filtrate. Metallic sulfonates are frequently purified further by recrystallization from water, often with the addition of brine to ensure a good yield by salting-out. 

Anthraquinone-l-sulfonate (Potassium Salt). The quinone is sulfonated with 20 per cent oleum in the presence of mercury sulfate catalyst. To ensure maximum yield, only 40 per cent of the starting material is reacted. 

To precipitate the desired potassium sulfonate, the filtrate [collected in receivers (3 and 3A), together with strong wash liquor] is transferred to the 20,000-liter rubber-lined precipitation tank (4) and the concentrated KCl solution is added. The temperature is maintained at 85°C to keep the byproduct 1,5-disulfonate in solution. The precipitated potassium sulfonate is isolated by continuous filtration on a rubber-covered rotary filter (5 and 6), where it is washed with 5 per cent potassium chloride solution and discharged at approximately 45 per hent solids content into a horizontal trough mixer (7), from which it is pumped to one of two 13,000-liter brick-lined paste storage tanks (8). The paste content is adjusted to 35 per cent solids and brought to neutrality with a small amount of soda ash solution, after which it is pumped either to an autoclave for conversion to 1-amino-anthraquinone or to the chlorinators for conversion to 1-chloroanthra-quinone. 

A mixture of caustic soda and potassium nitrate or chlorate possesses oxidizing powers, whereas caustic soda alone acts as a condensing and dehydrating agent. A good example of the use of the oxidizing mixture is in the formation of the dye alizarin from anthraquinone-/3-sulfonic acid, sodium salt. 

AQS = Anthraquinone-2-sulfonic acid M(TPS) = metal tetrasulfophthalocyanine BPS = bathephenanthroline disulfonic acid M(TPPS) = metal tetra(4-sulfophenyl)porphyrin PVSK = potassium poly(vinylsulfate) PSSNa = sodium poly(styrene sulfonate) Nafion = Salt of sulfonated and Wghly fluorinated polymer (trademark of Du Pont). 

Aminoanthraquinone is produced by the classic route from the potassium salt of anthraquinone-l-sulfonic acid with ammonia and sodium 3-nitrobenzenesulfo-nate at 175 °C and a pressure of 25 to 30 bar. The sodium 3-nitrobenzenesulfonate serves as an oxidizing agent for the sulfite which is released. 

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