Acid dyes anthraquinone

Anthraquinone Acid Dyes. Anthraquinone acid dyes are illustrated by Acid Blue 25 and Acid Green 25. These dyes are water-soluble anthraquinone derivatives that are used to dye wool, silk, nylon, leather, and paper. 

Dyes, Dye Intermediates, and Naphthalene. Several thousand different synthetic dyes are known, having a total worldwide consumption of 298 million kg/yr (see Dyes AND dye intermediates). Many dyes contain some form of sulfonate as —SO H, —SO Na, or —SO2NH2. Acid dyes, solvent dyes, basic dyes, disperse dyes, fiber-reactive dyes, and vat dyes can have one or more sulfonic acid groups incorporated into their molecular stmcture. The raw materials used for the manufacture of dyes are mainly aromatic hydrocarbons (67—74) and include ben2ene, toluene, naphthalene, anthracene, pyrene, phenol (qv), pyridine, and carba2ole. Anthraquinone sulfonic acid is an important dye intermediate and is prepared by sulfonation of anthraquinone using sulfur trioxide and sulfuric acid. 

Addition of sodium dithionite to formaldehyde yields the sodium salt of hydroxymethanesulfinic acid [79-25-4] H0CH2S02Na, which retains the useful reducing character of the sodium dithionite although somewhat attenuated in reactivity. The most important organic chemistry of sodium dithionite involves its use in reducing dyes, eg, anthraquinone vat dyes, sulfur dyes, and indigo, to their soluble leuco forms (see Dyes, anthraquinone). Dithionite can reduce various chromophores that are not reduced by sulfite. Dithionite can be used for the reduction of aldehydes and ketones to alcohols (348). Quantitative studies have been made of the reduction potential of dithionite as a function of pH and the concentration of other salts (349,350). 

The largest volume acid blues are either of triphenyhnethane (TPM) or anthraquinone chemical constituency (see Dyes, anthraquinone). 

Among anthraquiaoae dyes (see Dyes, anthraquinone). Acid Blue 78 [6424-75-5] C2 H25BrN20 S -Na, or Alizarin Pure Blue B, is a wool dye. Bromamine acid [116-81-4] (l-amiao-4-bromoanthraquiaoae-2-sulfonic acid), C24HgBrNO S, is a useful dye iatermediate. A number of bromo anthraquiaoae, pyrathroae, and benzanthrone dyes are known. 

The anthraquinones are useful in acrylics and are compatible with polystyrene and ceUulosics. Solvent Red 111 has a special affinity for poly(methyl methacrylate) as the red in automobile taillights exposure for a year in Florida or Arizona produces only a very slight darkening. Acid types are usehil for phenohcs (see Dyes, anthraquinone). 

In 1894 the first two anthraquinone acid dyes. Cl Acid Violet 43 [4430-18-6] (2) (Cl 60730) and Cl Acid Green 25 [4403-90-1] (3) (Cl 61570) were invented. This encouraged the subsequent development of various kinds of anthraquinone acid dyes, which were used to dye wool in fast, brilliant shades without need for pretreatment. 

In the 1950s acid dyes were successively developed to dye nylon carpet with excellent fastness and uniform leveling. Development of polyacrylonitrile fiber stimulated the invention of anthraquinone basic dyes, modified disperse dyes in which quaternary ammonium groups are introduced. 

Efforts to raise the alpha-selectivity have been made. Thus nitration of anthraquinone using nitrogen dioxide and ozone has been reported (17). l-Amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) [116-81 -4] (8) is the most important intermediate for manufacturing reactive and acid dyes. Bromamine acid is manufactured from l-aminoanthraquinone-2-sulfonic acid [83-62-5] (19) by bromination in aqueous medium (18—20), or in concentrated sulfuric acid (21). l-Aminoanthraquinone-2-sulfonic acid is prepared from l-aminoanthraquinone by sulfonation in an inert, high boiling point organic solvent (22), or in oleum with sodium sulfate (23). 

Many anthraquinone reactive and acid dyes are derived from bromamine acid. The bromine atom is replaced with appropriate amines in the presence of copper catalyst in water or water—alcohol mixtures in the presence of acid binding agents such as alkaU metal carbonate, bicarbonate, hydroxide, or acetate (Ullmaim condensation reaction). 

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). 

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 (see Chapter 1). These natural anthraquinone dyes are no longer of significant commercial importance. 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, hydroxy and methoxy, and a number of sul-fonated derivatives are commonly used as acid dyes for wool. 

Benzyl salicylate (10.176) at an applied concentration of 2% o.w.f. is reported [420] to have given good protection from fading to two anthraquinone acid dyes on silk. 

Atmospheric ozone has also been reported as causing fading of certain dyes in some countries [425,426] diallyl phthalate (10.182) used as a carrier in the dyeing of cellulose triacetate fibres, is said to be an effective ozone inhibitor [427]. Nylon, especially when dyed with certain amino-substituted anthraquinone blue acid dyes, can also be susceptible to ozone fading [428,429]. Selection of ozone-resistant dyes is obviously the best counteractive measure, although hindered phenols (10.161) and hindered amines (10.162) are said to provide some protection. 

Sphingomonas herbicidovorans Anthraquinone dyes The bacterium was capable of decolorizing bromoamine acid dye (1,000 mg L-1) more than 98% within 24 h [87]... 

Acid dye affinity, 19 759 Acid dyes, 9 184-186, 189-190, 215-216, 226, 243 26 395-396 anthraquinone, 9 301, 327-329 azo, 9 389-394 Acid dyestuffs, 9 223 Acid extractants, 10 750 Acid fixing reactive dyes, 9 478-481 Acid foods, heat preservation of, 12 80 Acid functional polyesters, 10 402 Acid gas constituents, 12 376-378 Acid gases, 10 612-613... 

It was pointed out in Chapter 1 that, after the azo class, anthraquinone derivatives form the next most important group of organic colorants listed in the Colour Index. The major application groups are vat dyes, disperse dyes and acid dyes (Table 1.1). 

Pigment Red 177 [4051-63-2] has the chemical structure of 4,4 -diaminol,l -dianthraquinonyl and is prepared by intermolecular copper-catalyzed debromination of l-amino-4-bromoanthraquinone-2-sulfonic acid followed by desulfonation. It is the only known pigment with unsubstituted amino groups which are involved in both intra- and intermolecular hydrogen bonding (19). The bluish red pigment is used in plastics, industrial and automotive paints, and specialized inks (see Dyes, ANTHRAQUINONE). 

I -Methylaminoanthraquinonc is an important intermediate for manufacturing solvent dyes and acid dyes, and is prepared from anthraquinone-1-sullonic acid by replacing the SOtH group with methylamine. 

Acid, basic, and direct dyes are all ionic in nature. Acid dyes contain free acid groups which are ionized in the aqueous application medium (dyebath). They generally used to dye polyamine, wool, or silk and are primarily azo, anthraquinone, or triarylmethane structures. 

Compared to direct azo dyes, the direct anthraquinone dyes have lower tinctorial strengths and are therefore far less economical to use. They have lost most of their importance. Only a few special green dyes have retained their importance. Direct green cotton dyes can be produced by coupling a blue bromamine acid dye and a yellow azo dye via ureido or diaminotriazine bridges. 

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