Anthraquinone sulfonic acid complexes

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 ... 

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. 

Anthraquinone dyes are characterized by the presence of one or more carbonyl groups in association with a conjugated system. These dyes also may contain hydroxy, amino, or sulfonic acid groups as well as complex heterocyclic systems. Anthraquinones uses include disperse, vat, acid, mordant, and fiber reactive applications. 

Acid dyes, i.e., azo or anthraquinone dyes containing sulfonic acid groups, were occasionally used for dyeing cotton however, they are no longer important. They do not have sufficient substantivity for cellulose. Only those dyes are usable that can form a metal complex on the fiber when applied together with a metal salt. Excess heavy metal contaminates the wastewater. 

The presence of mercuric salts in the sulfonation mixtures favors the formation of anthraquinone-1-sulfonic acid further sulfonation leads to a complex mixture of disulfonic acids, chiefly 1,5 and 1,8 with lesser quantities of 1,6 and 1,7-isomers [11]. 

Sulfamation of some of the residual amines with trimethylamine-SOo complex extends the water solubility of the i>olymeric dyes to basic pH ranges. An alternate route to such water soluble polymeric dyes is through the binding of the anthraquinone dyes to copolymers of vinylamine and vinyl sulfonic acid. 

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. 

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