Anthraquinone-2-sulfonic acid, derivatives

There are several cases of hydroxylation according to the hidden-radical mechanism, within a solvent cage. As assumed (Fomin and Skuratova 1978), hydroxylation of the anthraquinone sulfonic acids (AQ—SO3H) proceeds by such a reticent pathway, and OH radicals attack the substrate anion-radicals in the solvent cage. Anthraquinone hydroxyl derivatives are the final products of the reaction. In the specific case of DMSO as a solvenf, hydroxyl radicals give complexes with the solvent and lose their ability to react with the anthraquinone sulfonic acid anion-radicals (Bil kis and Shein 1975). The reaction stops after an anion-radical is formed ... 

Practically any aromatic hydrocarbon or aryl halide can be sulfonated if the proper conditions are chosen. As the compound becomes more complex, however, the tendency toward the production of by-products and mixtures of isomers is increased. It is usually difficult to prevent polysubstitution of a reactive hydrocarbon. For example, even when phenanthrene is sulfonated incompletely at room temperature, some disulfonic acids are formed. The sulfonation of anthracene follows such a complex course that the 1- and 2-sulfonic acid derivatives are made from the readily available derivatives of anthraquinone. The foUowii sections include comments.on the accessibility of the reaction products of the commonly available hydrocarbons and aryl halides. The examples cited and still others are listed in Tables I-XIII. 

The main by-products of the Ullmaim condensation are l-aniinoanthraquinone-2-sulfonic acid and l-amino-4-hydroxyanthraquinone-2-sulfonic acid. The choice of copper catalyst affects the selectivity of these by-products. Generally, metal copper powder or copper(I) salt catalyst has a greater reactivity than copper(Il) salts. However, they are likely to yield the reduced product (l-aniinoanthraquinone-2-sulfonic acid). The reaction mechanism has not been estabUshed. It is very difficult to clarify which oxidation state of copper functions as catalyst, since this reaction involves fast redox equiUbria where anthraquinone derivatives and copper compounds are concerned. Some evidence indicates that the catalyst is probably a copper(I) compound (28,29). 

Anthraquinone-l-sulfonic acid and Its Derivatives. Anthraquinone-l-sulfonic acid [82-49-5] (16) has become less competitive than 1-nitroanthraquinone as the intermediate for 1-aminoanthraquinone. However, it still has a great importance as an intermediate for manufacturing vat dyes via 1-chloroanthraquinone. 

Anthraquinone dyes have been produced for many decades and have covered a wide range of dye classes. In spite of the complexity of production and relatively high costs, they have played an important role in the areas where excellent properties ate requited, because they have excellent lightfastness and leveling properties with brUhant shades that ate not attainable with other chtomophotes. However, recent increases in environmental costs have become a serious problem, and future prospects for the anthraquinone dye industry ate not optimistic. Some traditional manufacturers have stopped the production of a certain dye class or dye intermediates that were especially burdened by environmental costs, eg, vat dyes and their intermediates derived from anthraquinone-l-sulfonic acid and 1,5-disulfonic acid. However, several manufacturers have succeeded in process improvement and continue production, even expanding their capacity. In the forthcoming century the woddwide framework of production will change drastically. 

Fat- and oil-soluble dyes are also soluble in waxes, resins, lacquers, hydrocarbons, halogenated hydrocarbons, ethers, and alcohols, but not in water. It is not possible to differentiate clearly between them and the alcohol- and ester-soluble dyes. With the exception of blue anthraquinone derivatives, fat- and oil-soluble dyes are azo dyes, generally based on simple components. According to their degree of solubility they usually contain hydroxyl and/or amino groups, but not sulfonic acid and carboxylic acid groups. Examples of fat- and oil-soluble azo dyes are C.I. 

The most important derivative employed in vat dye manufacture is the reduction product of 2-nitroanthraquinone, namely 2-aminoanthraquinone (61). It was formerly manufactured from the 2-sulfonic acid of anthraquinone, by reaction with ammonia in the presence of oxygen. However, sulfonation of anthraquinone requires mercury and the subsequent animation requires arsenic, making these processes ecologically unattractive. From the early 1970s, processes for direct nitration of anthraquinone at the 2-position, followed by reduction, were introduced, mainly as a result of research in Japan45,46. 

Excess Acid. The helpful function of excess sulfuric acid as an inexpensive, low-viscosity solvent for most sulfonic acids is often overlooked because of the difficulty of recovering a product dissolved in it, or because of the disposal problem often encountered. Sulfonation of most of the hydroxyl, amino, nitro, and carboxylic derivatives of benzene, naphthalene, and anthraquinone is facilitated in this manner by the presence of excess acid. The same effect applies to anthraquinone itself, to petroleum lubricant fractions during sulfonation to mahogany and green acids, and to the sulfation of fatty oils. Chlorosulfonic acid, used in large excess for the conversion of aromatic compounds to sulfonyl chlorides by chlorosulfona-tion, functions in a similar manner. 

Another striking observation is that the formation of the 2-acid can be depressed to as little as 1% by the use of pyridine-sulfur trioxide as the sulfonating agent, even when the reaction is carried out at temperatures (150-175°) that, with oleum, favor substitution in the 2-posi-tion. Although the two sulfonic acids can be separated from each other and from polysulfonic acids fairly adily by fractional crystallization of the sodium or barium salts, the sulfbnation reaction of anthracene is not employed commonly, since the monosulfonic acids are prepared more conveniently from the corresponding derivatives of anthraquinone. 

Among derivatives of sulfonic acid, the following are suitable for identification heavy-metal salts, chlorides, and crystalline sulfonamides (formed from chlorides and organic bases). To identify anthraquinone-... 

When anthraquinone is sulfonated in the presence of mercury sulfate, the results differ from those just described. A single sulfonic acid group enters at position 1, whereas two groups enter to form the 1,5- and 1,8-disulfonic acids. The 1,5-isomer is salted out from the more soluble 1,8-isomer after dilution of the sulfonation mass. The 1,5- and 1,8-disulfonic acids are of great importance for the manufacture of other derivatives, which can be made by replacement of the sulfonic acid groups. Examples are the chloro-and hydroxyanthraquinones. 

Other Acid Anthraquinone Dyes. In addition to the dyes in the preceding classes, a whole series of specially developed products is available. For instance, derivatives of the anthrimide or carbazole series are known to be very light-fast gray and brown wool dyes. The post-sulfonation products of 1,5- and 1,8-diarylami-noanthraquinones are violet dyes commonly applied as mixtures. 

Derivation Anthraquinone is sulfonated with fuming sulfuric acid in the presence of mercury or mercuric oxide to a mixture of the 1,5- and 1,8-disulfon-... 

FIGURE 9.3 Structures of benzene, naphthalene, and anthracene derivatives analyzed sodium benzenesulfonate (1), 4-chloroaniline (2), 3,4-dichloroaniline (3), 2-naphthylamine (4), sodium 2-naphthalenesulfonate (5), sodium anthraquinone 2-sulfonate monohydrate (6), 1,2-diamineanthraquinone (7), 2-anthraceencarboxilic acid (8), and 2-anthramine (9). 

There is a wide diversity of chemical structures of anthraquinone colorants.Many anthraquinone dyes are found in nature, perhaps the best known being alizarin, 1,2-dihydroxyanthraquinone, the principal constituent of madder (Chapter 1). Naturally-based anthraquinone dyes are of limited current commercial importance, although synthetic alizarin, as Cl Mordant Red 11, is used to an extent in the dyeing and printing of natural fibres. Many of the current commercial range of synthetic anthraquinone dyes are simply substituted derivatives of the anthraquinone system. For example, a number of the most important red and blue disperse dyes for application to polyester fibres are simple non-ionic anthraquinone molecules, containing substituents such as amino, hydroxyl and methoxy, and several sulfonated derivatives are commonly used as acid dyes for wool. 

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