Violet reactive dyes

Violet leaf absolute Violet reactive dyes Viologens... 

Copper and chromium are used for complexing a number of dyes such as the coppered direct and reactive dyes for cotton and metaUi2ed and neutral metal complex acid dyes for nylon, wool, etc. Examples are Direct Blue 218 [28407-37-6] (Cl 24401) (317), Reactive Violet 2 [8063-57-8] (Cl 18157) (318), and Acid Black 52 [5610-64-0] (Cl 15711) (319). 

The formation and isolation of solid complexes between cyclodextrins and reactive dyes have been reported, but no dyeing results were presented [29]. Complexes were formed between P-cyclodextrin and Cl Reactive Orange 16, Violet 5, Blue 38 or Blue 114 and between y-cyclodextrin and Cl Reactive Blue 38 or Blue 114. 

The 1 1 copper complex azo dyes are used both as reactive dyes for cotton and as direct dyes for paper. (For definitions of reactive dyes, which form covalent linkages with the substrate, and direct dyes, which bind more weakly, see refs. 23 and 24, respectively.) Typical monoazo dyes are Cl Reactive Violet 1 (23) and Cl Reactive Blue 13 (25), and the bis-copper-ed dye, Cl Direct Blue 80 (26). The navy blue dye, Cl Reactive Blue 82 (27), is a typical disazo dye. 

The high visibility of water-soluble dyes released to the environment ensures that only extremely low concentrations in watercourses would not be noticed. A typical visibility limit in a river would be about 0.1 to 1 mg/1, but this varies with the colour, illumination and degree of clarity of the water. The human eye can detect a reactive dye concentration as low as 0.005 mg/1 in pure water, particularly in the red to violet hue sector [88]. There is considerable debate, however, about what level of environmental hazard is represented per se by colour in effluent. The view has been expressed that dyestuffs should not be regarded as water pollutants because at concentrations of the same order of magnitude as these visibility limits their harmful effects are negligible [89]. Nevertheless, even though this colour problem is mainly if not entirely an aesthetic one, the fact is that the general public will not tolerate coloured amenity water and the problem therefore has to be addressed and rectified [90,91,92],... 

Triphenodioxazine compounds have been used to make brilliant blue direct and reactive dyes for cellulosic fibres, but only one pigment in this chemical class, Cl Pigment Violet 23 (2.43), is widely used. It is prepared by condensing 3-amino-9-ethylcarbazole with chloranil in trichlorobenzene [29]. As with many other pigments, manufacturers offer it in many physical forms adapted to the intended end-use. 

In contrast to direct dyes, metal-complex azo reactive dyes are almost always monoazo chromogens coordinated to one copper(II) ion per molecule. The important structural types include phenylazo J acid reds (5.47), phenylazo H acid violets (5.48) and naphthylazo H acid blues (5.49), where Z represents the reactive system attached through the imino group in the coupling component. Less often the reactive system is located on the diazo component, as in Cl Reactive Violet 5 (5.50) and analogous red to blue members of various ranges. 

The dioxazine ring system is the source of some valuable violet pigments, such as Cl Pigment Violet 23 (6.211). This colorant is obtained by condensing 3-amino-9 ethylcarbazole with chloranil. Sulphonation of the pigment gives the dye Cl Direct Blue 108. Triphenodioxazines have recently been the source of some blue reactive dyes [241-Examples are known of symmetrical bifunctional structures (6.212 NHRNH = alkylenediamine, Z = haloheterocyclic system) and unsymmetrical monofunctional types such as 6.213 [37]. 

Native Cassia angustifolia (CA) seed gum with 1 mL of PAC stock solution at highly acidic pH (pH = 2.5) has been shown to remove 35% Acid Sendula Red, 22% Direct Kahi Green, and 16% Reactive Remazol Brilliant Violet dyes [9] while at alkaline pH (pH = 10) under identical conditions, the decol-orization efficiency of CA is reported to be about 80%, 99%, and 45% for acid, direct and reactive dyes, respectively. CA acts as a good working substitute... 

The manufacture of crystal violet (1), however, is a special case which does not involve the isolation of the intermediate Michler s ketone (Fig. 3). Thus, phosgene is treated with excess dimethyl aniline in the presence of zinc chloride. Under these conditions, the highly reactive intermediate "ketone dichloride" is formed in good yield this intermediate further condenses with another mole of dimethyl aniline to give the dye. 

Many red dyes are based on H-acid [90-20-0] (11), eg, Reactive Reds 2, 24, and 218. Others are substituted phenyl and naphthyl or metallised systems (7) (Table 2). Violet dyes are also metallised monoaso dyes (7). 

Reduction of Methylene Violet with zinc in acetic acid gives the air-sensitive leuco 20 which is further reacted with acetic anhydride in mild conditions to yield the acetylated leuco 21. The latter being air stable can be isolated and, the ring N-H being less reactive is not affected by acetylation at room temperature. The leuco 21 is again aroylated to produce the leuco 22. Selective hydrolysis provides the desired leuco dye 12 which regenerates the true Methylene Violet (6) on oxidation.83... 

The most important 2 1 metal complex azo dyes are the 2 1 Cr3+ dyes. These may be symmetrical dyes, such as the water-soluble dye Cl Reactive Brown 10 (28), and the solvent-soluble dye Cl Solvent Yellow 21 (29), used in varnishes as a wood stain. They may also be unsymmetrical complexes, such as Cl Acid Violet 121 (30), used for dyeing wool and nylon. 

Moosvi S, Keharia H, Madamawar D (2005) Decolorization of textile dye Reactive Violet 5 by a newly isolated bacterial consortium RVM11.1. World J Microbiol Biotechnol 21 667-672... 

Another reactive component for leather (major use dyeing wool) is thea-sul-fatoethylsulfonyl group, as in e.g., C.l. Reactive Violet 4, 17965 [12769-08-3] (1 1 Copper 21), as well as acryloamido, e.g., a-bromoacryloamido groups. 

Eight sulfonated azo dyes (Acid Red 1, 8, 29, and 106, Acid Violet 5, Reactive Red 2 and 4, Reactive Orange 16) were individually characterized with respect to major components using a base deactivated C g column (A = 254nm). Isocratic mobile phase compositions of 35/65 to 50/50 methanol/water (50 mM ammonium acetate) were used (dye specific). Typical run times were 40-60 min... 

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