Anthraquinone Constitution

Acid—mordant dyes have characteristics similar to those of acid dyes which have a relatively low molecular weight, anionic substituents, and an affinity to polyamide fibers and mordant dyes. In general, brilliant shades caimot be obtained by acid—mordant dyes because they are used as their chromium mordant by treatment with dichromate in the course of the dyeing procedure. However, because of their excellent fastness for light and wet treatment, they are predominandy used to dye wool in heavy shades (navy blue, brown, and black). In terms of chemical constitution, most of the acid—mordant dyes are azo dyes some are triphenyhnethane dyes and very few anthraquinone dyes are used in this area. Cl Mordant Black 13 [1324-21 -6] (183) (Cl 63615) is one of the few examples of currentiy produced anthraquinone acid—mordant dyes. It is prepared by condensation of purpurin with aniline in the presence of boric acid, followed by sulfonation and finally by conversion to the sodium salt (146,147). 

Anthraquinone.—The constitution of anlhraqinnone is demed fiom various syntheses, such as the action of zinc dust on a mixture of phthalyl chloride and benzene, or by lieating benzoyl benzoic acid with II,Or,... 

This chapter classifies polycyclic pigments by chemical constitution. The resulting classes include aminoanthraquinones, hydroxyanthraquinones, heterocyclic and polycarbocyclic anthraquinone pigments. 

On the basis of their chemical constitutions the anthraquinoid vat dyes may be classified in the following major groups acylaminoanthraquinones, anthraqui-noneazoles, anthrimides and other linked anthraquinones, anthrimidocarbazoles, phthaloylacridones, benzanthrone dyes, indanthrones, and other polycondensed ring systems. 

Anionic dyes include many compounds from the most varied classes of dyes, which exhibit characteristic differences in structure (e.g., azoic, anthraquinone, triphenylmethane, and nitro dyes) but possess as a common feature water-solubilizing, ionic substituents. The anionic azo dyes which are discussed here constitute the most widely used group of this class of dyes. 

From about 1930 onwards, developments in the field of naphthoquinone dyes concentrated on the use of naphthazarin and intermediates for the preparation of violet, blue, and green acid and disperse dyes [1]. More recently there has been interest in the synthesis and color and constitution properties of simple colored naphthoquinones, stimulated by the fact that such dyes have similar tinctorial properties to the anthraquinones but a smaller molecular size. The naphthoquinones provide a useful alternative to the anthraquinones for certain specialized applications, e g., as pleochroic dyes with improved solubility for liquid-crystal displays. As a result, research interest in these chromogens remains unabated, even though they have failed to make any major impact as textile dyes [2-8],... 

Reactive dyes are colored compounds that contain groups capable of forming covalent bonds between dye and substrate. Approximately 80-90% of reactive dyes are azo dyes. The other chromogenic classes are anthraquinones, dioxazines, phthalocyanines, and some 1 1 copper azo complexes. Reactive 1 2 complex leather dyes were also commercially manufactured for a short time. Constitution and producer have not been disclosed. 

The features of chemical constitution associated with the special requirement of solvent solubility include a number of chemical groups on the chromophores. Sulfo groups are often absent, and only hydroxy or amine groups are present. There are mostly cationic and neutral and sometimes also anionic azo, 1 2 azo metal-complex, and a few anthraquinone dyes. An example is C.I. Solvent Yellow 21, 18690 [5601-29-6] (22, 1 2 Chrome alsoC.7. Acid Yellow 121). 

The wide varity of anthraquinone dyes identified in various madder plants is not to be found in the dye insects American cochineal, kermes, Polish and Armenian cochineal. These insects contain two dyes whose constitutions are known and a third dye whose constitution has not yet been clarified. However, the fifth in the class of dye insects, lac dye, contains five water-soluble dyes ( = laccaic acids) and traces of three water-insoluble dyes. 

Disperse dyes are relatively small molecules, with very low water solubility, which possess a high affinity for hydrophobic fibres such as cellulose acetate, polyester or blends thereof. The dyes are applied by transfer printing or high temperature steam fixation. Azo and anthraquinone dyes constitute the major portion of disperse dyes. 

The constitutions of anthracene and anthraquinone are thus established as reciprocal oxidation and reduction products. The complete structural formulas may be represented as follows ... 

As will be seen, only these two mono-hydroxy compounds are possible. Now both of these mono-hydroxy anthraquinones yield alizarin by the introduction of a second hydroxyl group. The only constitution possible for a di-hydroxy anthraquinone obtained from both of these two mono-hydroxy anthraquinones is the 1-2-di-hydroxy compound. As alizarin is thus obtained the two hydroxyl groups in it must be in the 1-2 positions and not in the 2-3 positions. 

This analogy is especially marked if the constitutional formula of anthraquinone is compared with that of the simplest aromatic azine. 

The direct oxidation of benzene into phenol constitutes one of the challenges in chemistry to substitute the cumene process at the industrial level. Such oxidation has also been achieved with several TpfCu complexes as catalysts, leading to moderate yields and high selectivity toward phenol, in a transformation using hydrogen peroxide as the oxidant and at moderate temperatures. The same catalytic system has been employed for the selective oxidation of anthracenes into anthraquinones (Scheme 24). 

Anthranoid laxative plants The anthranoid-containing plants are essentially similar in their mode of action. In this group the active substances are a group of polynuclear or tricyclic hydrocarbon derivatives based on anthracene. Various oxidised and reduced forms constitute the aglycones of a variety of C and O glycosides. The fully oxidised form is the anthraquinone form, with the partially reduced form represented by the an-throne nucleus. Dimeric forms whereby two anthracene nuclei are chemically linked to... 

Anthraquinone derivatives also constitute a commercially important class of vat dyes for dying synthetic fibres [13]. Many anthraquinones are used as photoinitiator for crosslinking or degradation of polyethylene. In the present article, an effort is made to capture the essence of these studies in quinones and also point out some future prospects. 

The Friedel-Crafts reaction is an important reaction in organic synthesis and is widely used for the substitution of a side chain in an aromatic ring with AICI3 as catalyst. The reaction between benzene and phthalic anhydride, which constitutes a step in the preparation of anthraquinone, is one such reaction. We give below the chemist s and the chemical engineer s ways of looking at this reaction (see Rose, 1981, for a detailed discussion). ... 

A typical spectrum of anthraquinone dyes (Color Index Constitution... 

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