Reactive Anthraquinone Dyes

Copper complexes of the formazan dye series (see Sections 2.10 and 3.11) are another alternative to reactive anthraquinone dyes they produce red to greenish-blue shades. Like triphenodioxazine dyes, copper formazans exhibit high molar extinctions ( e = 25 000 -30 000). These materials are derived from l-(2-hydroxyphe-nyl)-3-phenyl-5-(2-carboxyphenyl)formazan (22), in which all three rings are capable of supporting groups that increase the compound s reactivity and solubility. 

MuUer B (2007) Fibre-reactive anthraquinone dyes, process for their preparation and the use thereof. US Patent 2007/151049, 5 July 2007... 

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. 

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. 

Production of anthraquinone reactive dyes based on derivatives of bromamine acid (8) was first commercialized in 1956. Some improvements have been made and now they ate predominandy used among the reactive blue dyes. Cl Reactive Blue 19 [2580-78-1] (9) (Cl 61200) (developed by Hoechst in 1957) has the greatest share among them including dye chromophores other than anthraquinones. 

Two different chemical classes contribute to this sector. Initially it was entirely dominated by anthraquinone dyes typified by structure 7.102. The dye bases for attachment of haloheterocyclic (Z) systems are prepared by condensing bromamine acid (7.103) with various phenylenediamines. The outstandingly successful Cl Reactive Blue 19 (7.3 7) is the... 

These chromophores have declined significantly in importance as textile dyes bnt have remained of interest becanse of their fluorescent behaviour, as discussed in Chapter 3, section 3.5.1.5. One exception is the triphenodioxazine ring system, which is used to produce valuable blue dyes in the Direct (2.19) and Reactive dye classes (2.20) as well as pigments (see section 2.4.1.7). The dyes from this chromogen have a very high molar absorption coefficient (ca. 80 000) versus typical anthraquinone dyes (ca. 15 000) and have therefore replaced some of the dyes from this latter chromogen in the reactive dyeing of cotton. ... 

In a DTA study of 14 anthraquinone dyes, most had high flash points (225—335°C) and ignition points (320—375°C). Purpurin dianilide [107528-40-5] was exceptional with the much lower values of 110 and 155°C, respectively [1]. A similar study of indigo type dyes and vat solubilised modifications is reported. The basic dyes decompose over 350°C, destabilised to around 200°C for solubilised dyes. The relation between functional groups, structure and flammability is discussed [2]. Sulfonyl azides have been employed for attachment of reactive dyes, it is claimed they are safer used in supercritical carbon dioxide than in water [3]. 

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. 

When the substrate does not possess any hydrogen atom liable to be replaced by the aminomethyl group, aminomethylation can take place equally through the substitution of a sufficiently reactive X group (route b in Fig. 8), without modification of the R moiety in the substrate. This is the case of the anthraquinone dye 10 (Fig. 10), which gives a Mannich base derived by the replacement of the sulfonic group. " ... 

Judging from the colour removal efficiencies indicated in Table 14, the solubility of the dye molecules was the dominant parameter for the photodecomposition. Anthraquinone dyes were UV intact due to their chemical structure (Leaver I.H., 1980). Nevertheless, the results from samples 3 to 6 suggested that the solubility was another critical factor to hinder their UV decomposition. The sulphonate anthraquinone reactive dye (sample 6 in figure 8), for example, had a much greater colour removal rate in the experiment (36.8%)... 

One hydrophilic anthraquinone dye (Al) and one hydrophobic anthraquinone dye (A2) were selected to explore the effect of solubility to the UV-irradiation. From the experimental data, the hydrophilic anthraquinone dye (sulphonate anthraquinone reactive dye) has about twice the dye removal rate than hydrophobic anthraquinone dyes at high pH. Since all the anthraquinone dyes have similar chemical structures and the pH did not show any distinguish effect in dye removal for A2, it is obvious that the rate difference is mainly due to the difference of solubility. The effect of dye s solubility to the photodegradation may be interpreted by the photo-ionization mechanisms proposed by Leaver I.H. (1980). The water can carry the charged intermediates (Al only), which lower the photo-ionization energy and therefore facilitate the dye degradation. 

Epolito WJ, Lee YH, Bottomley LA, Pavlostathis SG. Characterization of the textile anthraquinone dye Reactive Blue 4. Dyes Pigments 2005 67(1 ) 35-41. 

Anthraquinone dyes have anthraquinone as their base and the carbonyl group (>C=0) as the chromophore. Anthraquinone itself is not a contact allergen. In fact, the anthraquinone ACD dyes have no obvious protein reactive group or substructure for reaction... 

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). 

Reactive dyes generally contain colored anthraquinones with various reactive groups attached to the nonchromophotic portions of the molecule. 

A recent addition to Table 3, Reactive Blue 246 differs from the other dyes and is not added to a finished lens. The dye molecule has methacrylate groups attached to an anthraquinone and is incorporated directiy into the polymer matrix during polymer cure (175). This in-monomer concept has the potential to reduce dramatically the cost of visibiUty tinting of a contact lens. 

World dye manufacturers have already begun to develop new types of dyes that can replace the anthraquinones technically and economically (1). Some successful examples can be found in a2o disperse red and blue dyes. Examples are brilliant red [68353-96-6] and Cl Disperse Blue 165 [41642-51 -7] (Cl 11077). They have come close to the level of anthraquinone reds and blues, respectively, in terms of brightness. In the reactive dye area intensive studies have continued to develop triphenodioxa2ine compounds, eg, (13), which are called new blues, to replace anthraquinone blues. In this representation R designates the substituents having reactive groups (see Dyes, reactive). 

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