Anthraquinone dye

Dyes derived from the triphenodioxazine ring system (18) have been commercially available since 1928 when Kranzlein and coworkers discovered dyes with this basic structure augmented by sulfonic acid groups. The unsubstituted triphenodioxazine (which is of no importance as a colorant) was first obtained by G. Fischer in 1879 [39], and its structure 18 was elucidated in 1890 [40], 

By varying the substituents on the orange parent substance 19, particularly in the positions para to the imino groups, its color can be modified. Red to red-violet shades result when X=OH or O R, and blue colors when X=NH2 or NHR. A blue shade also results if the external phenyl groups of the dioxazine system are part of an annulated and highly condensed aromatic ring system, for example, pyrene (C.I. Direct Blue 109, [33700-25-3]). 

The first commercial products of this type were sold as blue direct dyes with unmatched tinctorial strength, brilliance, and high lightfastness. An example is C.I. DirectBlue 106, 51300 [6527-70-4] (20)  

The triphenodioxazine chromophore was tested in almost every class of dyes, but only recently has it been introduced into reactive dyes. Dioxazines were investigated in some of the earliest work on reactive dyes in the late 1950s, and they are included in some of the first patents covering reactive anchors and reactive dyes [42], In particular, compound 21 was invoked as a chromophore, with reactive anchors attached to the free amino groups of the molecule. 

The launching of these new products initiated research by other dye manufacturers. This led to numerous new dioxazine reactive dyes (Examples see Table 2.3). 

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It is an important dyestuffs intermediate. It condenses with chloroethanoic acid to give phenylglycine-o-carboxylic acid for the synthesis of indigo. It can be diazotized and used as a first component in azo-dyes it condenses also with chloroanthraquinones to give intermediates for anthraquinone dyes. 

AMNES - AMINES,AROMATIC - PHENYLENEDIAMINES] (Vol2) -anthraquinone dyes [DYES, ANTHRAQUINONE] (Vol8)... 

There is a wide variety of dyes unique to the field of hair coloring. Successive N-alkylation of the nitrophenylenediamines has an additive bathochromic effect on the visible absorption to the extent that violet-blue dyes can be formed. Since the simple A/-alkyl derivatives do not have good dyeing properties, patent activity has concentrated on the superior A/-hydroxyalkyl derivatives of nitrophenylenediamines (29,30), some of which have commercial use (31). Other substituents have been used (32). A series of patents also have been issued on substituted water-soluble azo and anthraquinone dyes bearing quaternary ammonium groups (33). 

Azine, oxazine, and thiazine dyes were historically more important than they are at present. However, at least one example of each, introduced more than 100 years ago, is still offered commercially today (1,2). Azo and anthraquinone dyes have largely displaced them in commercial appHcation. Azo dyes (qv) offer better fastness and broader shade ranges at more economical prices. 

One of tfie most important applications of 4-chloiophenol is in the synthesis of derivatives of quinizarin [81-64-17, anthraquinone dyes (see Dyes,... 

Organic colors caused by this mechanism are present in most biological colorations and in the triumphs of the dye industry (see Azinedyes Azo dyes Eluorescent whitening agents Cyanine dyes Dye carriers Dyes and dye intert diates Dyes, anthraquinone Dyes, application and evaluation Dyes, natural Dyes, reactive Polymethine dyes Stilbene dyes and Xanthenedyes). Both fluorescence and phosphorescence occur widely and many organic compounds are used in tunable dye lasers such as thodamine B [81-88-9], which operates from 580 to 655 nm. 

Anthraquinone Dyes. These dyes have much supeiioi weatheiabihty and heat stabihty compared with the azos, but at higher cost. Typical examples ate Solvent Red 111, Disperse Violet 1, Solvent Blue 56, and Solvent Green 3. 

Dyes may be classified according to chemical stmcture or by thek usage or appHcation method. The former approach is adopted by practicing dye chemists who use terms such as a2o dyes, anthraquinone dyes, and phthalocyanine dyes. The latter approach is used predominantiy by the dye user, the dye technologist, who speaks of reactive dyes for cotton and disperse dyes for polyester. Very often, both terminologies are used, for example, an a2o disperse dye for polyester and a phthalocyanine reactive dye for cotton. 

The carbocychc azo dye class provides dyes having high cost-effectiveness combined with good all-around fastness properties. However, they lack brightness, and consequendy, they cannot compete with anthraquinone dyes for brightness. This shortcoming of carbocychc azo dyes is overcome by heterocychc azo dyes. 

Heterocyclic Azo Dyes. One long-term aim of dyestuffs research has been to combine the brightness and high fastness properties of anthraquinone dyes with the strength and economy of azo dyes. This aim is now being realized with heterocychc azo dyes, which fall into two main groups those derived from heterocychc coupling components, and those derived from heterocychc diazo components. 

Anthraquinone Dyes. This second most important class of dyes also iacludes some of the oldest dyes they have been found ia the wrappiags of mummies dating back over 4000 years. In contrast to the a2o dyes, which have no natural counterparts, all the important natural red dyes were anthraquiaones (see Dyes, natural). However, the importance of anthraquiaone dyes is declining due to their low cost-effectiveness. 

The appearance of synthetic fibers in the 1920s accelerated the further development of anthraquinone dyes. Soon after British Celanese succeeded in commerciali2ing cellulose acetate fiber in 1921, anthraquinone disperse dyes for this fiber were invented by Stepherdson (British Dyestuffs Corp.) and Celatenes (Scottish Dyes) independendy. Anthraquinone disperse dyes for polyester fiber were developed after the introduction of this fiber by ICI and Du Pont in 1952. These dyes were improved products of the disperse dyes that had been developed for cellulose acetate fiber 30 years before. 

Some anthraquinone dyes are employed as organic pigments (see Pigments, organic). Examples appear in Figure 1. Indanthrone blue (6) is an important automotive paint pigment as is Cl Pigment Red 177 (7), a bisanthraquinonyl. 

Fig. 1. Anthraquinone dyes used as organic pigments (4) = dibromoan than throne [4378-61-4] (Cl Pigment Red 168 Cl Vat Orange 3 Cl 5930G) (5) = an anthrapyrimidine [4216-01 -7] (Cl Pigment YeUow 108 Cl Vat YeUow 20 Cl 68420)-, (6) = indanthrone blue [81-77-6] (Cl Pigment Blue 60 Cl Vat Blue 4 ...

The synthesis of an anthraquinone dye generally involves a large number of steps. For example. Cl Disperse Red 60 [17418-58-5] (10) (Cl 60756) (a typical disperse red dye) requites five steps starting from anthraquinone, and Cl Disperse Blue 56 [31810-89-6] (11) (Cl 63285) requites six steps. 

In addition to the color and the tinctorial strength, which ate very important factors for the molecular design of anthraquinone dyes, affinity for fibers, various kinds of fastness (light, wet, sublimation, nitrogen oxides (NO ) gas, washing, etc), and apphcation properties (sensitivity for dyeing temperature, pH, etc) must be considered thoroughly as well. 

Anthraquinone dyes are derived from several key compounds called dye intermediates, and the methods for preparing these key intermediates can be divided into two types (/) introduction of substituent(s) onto the anthraquinone nucleus, and (2) synthesis of an anthraquinone nucleus having the desired substituents, starting from benzene or naphthalene derivatives (nucleus synthesis). The principal reactions ate nitration and sulfonation, which are very important ia preparing a-substituted anthraquiaones by electrophilic substitution. Nucleus synthesis is important for the production of P-substituted anthraquiaones such as 2-methylanthraquiQone and 2-chloroanthraquiaone. Friedel-Crafts acylation usiag aluminum chloride is appHed for this purpose. Synthesis of quinizatia (1,4-dihydroxyanthraquiQone) is also important. 

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). 

In order to develop the dyes for these fields, characteristics of known dyes have been re-examined, and some anthraquinone dyes have been found usable. One example of use is in thermal-transfer recording where the sublimation properties of disperse dyes are appHed. Anthraquinone compounds have also been found to be usehil dichroic dyes for guest-host Hquid crystal displays when the substituents are properly selected to have high order parameters. These dichroic dyes can be used for polarizer films of LCD systems as well. Anthraquinone derivatives that absorb in the near-infrared region have also been discovered, which may be appHcable in semiconductor laser recording. 

The dyes used in the ink sheet must satisfy various requirements (/) optimum color characteristics of the three primary colors (hue, color density, shape of absorption spectmm) (2) sensitivity, ie, sublimabiHty from ink sheet to acceptor sheet (3) fastness for light and migration and (4) compatibiHty with the resin in the ink sheet. With respect to these characteristics, a large number of anthraquinone dyes have been proposed particularly for magenta and cyan colors. Typical examples are given in Table 8 and Table 9. 

Several basic chromophore stmctures have been proposed for this purpose. Anthraquinone dyes appear to be predominant since they have a wider color range, excellent photostabiHty, good solubiHty in Hquid crystal media, and very high order parameters. Typical basic stmctures of the three primary colors are illustrated in Figure 11. Some examples are given in Table 10. The appropriate combination of three primary colors gives a black display. 

Table 11. Some Examples of Anthraquinone Dyes for Polarizer Films ...

Anthraquinone dyes are derived from several key compounds, ie, dye intermediates. Production of these dye intermediates often requires sophisticated production processes and a large amount of investment in plant constmction. The competitiveness of final products, dyestuffs, depends on that of the intermediates, ie, quaUty, cost, and availabiUty. 

Production Capacity and Demand. The production capacity for each dye or dye intermediate has rarely been aimounced officially by the individual manufacturers. However, the world demand of anthraquinone colorants can be roughly estimated as in Table 13 and, more specifically, in Figure 13. Principal manufacturers of anthraquinone dyes and their intermediates are as follows ... 

In addition to these, some anthraquinone dyes and their intermediates are also produced in Eastern Europe, Russia, China, and Korea. As the result of the history of anthraquinone chemistry, most manufacturers are still located in Western Europe. Most former manufacturers in the United States abandoned the dyestuff business or were acquired by European companies by the middle of the 1980s. 

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. 

Consumption. Anthraquinone dyes are the most important dye class after azo dyes. Wodd textile production is estimated in Table 14. Estimates of the consumption of dyes for textiles ate given in Figure 14, together with the figures for fiber consumption. This shows that the consumption of each dye class or classes is approximately parallel to the consumption of fibers to which they ate apphed. 

Anthraquinone Dyes. Simple anthraquiaone dyes are used mainly to obtain bright reds, pinks, blues, greenish blues, turquoises, and bluish greens. They give a purer and brighter shade than found with most commonly available a2o dyes (see Dyes, anthraquinone). 

Two large studies were done (250,251) for the selection of a2o, nitro, and anthraquinone dyes for carcinogen bioassay. Based on previous information or testing, a total of 30 dyes were selected based on chemical stmcture, potential exposure, and suspicion of carcinogenicity. 

Alizarin. There is only one significant plant anthraquinone dye, alizariu [72-48-0] (Cl Natural Red 6, 8, 9,10, 11, and 12 Cl 75330). In ancient times, alizaria was the preferred red dye. Cloth dyed with it has been found in Egyptian tombs dating 6000 years ago. The dye is found in the madder plant, a member of the Rubiaceae family. In 1944 about 35 species of this plant were known (1), but the use of more sophisticated analytical methods led to the detection of many more species by 1984 the number had increased to 50 (2). Of these, tinctorum and R peregrina yield the greatest amount of dye,... 

Carmine [1390-65-4] is the trade name for the aluminum lake of the red anthraquinone dye carminic acid obtained from the cochineal bug. The dye is obtained from the powdery form of cochineal by extraction with hot water, the extracts treated with aluminum salts, and the dye precipitated from the solution by the addition of ethanol. This water-soluble bright red dye is used for coloring shrimp, pork sausages, pharmaceuticals, and cosmetics. It is the only animal-derived dye approved as a colorant for foods and other products. 

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