Acid green dyes

Among the acid colors of green, brown, and black shades, three disazo dyes are important Acid Green 20 (42) -nitroaniline------ H-acid... 

The only nitroso dyes important commercially are the iron complexes of sulfonated l-nitroso-2-naphthol, eg. Cl Acid Green 1 [57813-94-2] (78) (Cl 10020) these inexpensive colorants are used mainly for coloring paper. 

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. 

Reactive green dyes are obtained by combination of a blue chromophore (a bromamine acid derivative) and a yellow chromophore with a tria2inyl group. Green [70210-47-8] (87) (104) is an example. The yellow chromophore of this dye was invented by ICI for diclilorotria2ine dyes and exhibits good lightfastness and chlorine resistance. 

The decolorization potential of immobilized P. chrysosporium MTCC 787 for azo dyes Acid Orange, Acid Red 114, triphenylmethane dye Methyl Violet, diazoic dye Congo Red, vat dye Vat Magenta, thiazine dye Methylene Blue, and anthraqui-none Acid Green was demonstrated by Radha et al. [53]. Decolorization experiments were carried out with immobilized calcium alginate (Ca-ALG) beads of different sizes (2-6 mm). 

They found the percentage decolorization decrease with increasing bead diameter for all dyes. Adsorption was determined by Ca-ALG beads (without immobilization) and it showed an initial reduction of 20% of the color. The immobilized fungus in Ca-ALG beads showed a low K,lyl. value for the Congo Red, a high K,lyl. value for Acid Orange and almost a constant value for Acid Red 114. They reported that P. chrysosporium was not able to decolorize Acid Green at a concentration... 

Not many green anthraquinone disperse dyes are available commercially. One example is Cl Disperse Green 6 1 (6.53), which has wider use as Cl Solvent Green 3 and is the precursor of Cl Acid Green 25 (6.27). 

Condensation of a diphenylmethanol derivative, such as Michler s hydrol (6.159), with a reactive aryl component under acid conditions (the hydrol synthesis) also provides a leuco base. The dye 6.163 (Cl Acid Green 50) is made by reacting Michler s hydrol with R acid (2-naphthol-3,6-disulphonic acid) and oxidising the resulting leuco compound (Scheme 6.30). 

Figure 9. Structures of azo dyes acid green 25 (AG25), basic blue 9 (BB9), direct red 23 (DR23), acid orange 7 (A07) and amaranth (Am).

Bilirubin effects depend on the method used for analysis. Interferences in direct serum protein methods are observed at bilirubin levels greater than 5 mg/100 ml (K7). A sample containing 20 mg of bilirubin per 100 ml increased the apparent total protein by 0.2 g/100 ml. Concentrations of bilirubin as high as 20 mg/ml do not effect albumin assays using bromocresol green binding (D12), but have a marked effect on these assays when [2-(p-hydroxyphenylazo)-benzoic acid] (HABA) dye is used (A7b). 

Benzaldehyde may be detected by the appearance of a blue color on treating with acenaphthene and H2S04, followed by heating. Benzaldehyde is used (1) as a flavoring material, (2) in the production of cinnamic acid. (3) in the maniifacrnre of malachite green dye. 

Using 2NpOH and 2-naphthol-3,6-disulfonate [121] as excited-state proton emitters, a transient high proton concentration is achieved on the membrane surface. With bromocresol green dye adsorbed on the membrane serving as a pH indicator, it has been found that the protons first react with the acidic ionized moieties on the surface and then reach the strongest base on the surface by rapid exchange. 

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. 

Brominated condensation products can be obtained by using appropriately halogenated naphthoxidine intermediates such as 19. For example, 19 can be condensed with aniline in acetic acid at 90 °C to give 20 [1], Naphthoxidine and its brominated derivatives can also be condensed with aminoazo compounds to give mixed azo-quinone chromogens, e.g., 21. These are of interest as homogeneous green dyes [1]. 

Sakthivel, S., B. Neppolian, M. Palanichamy, B. Arabindoo and V. Murugesan (1999). Photocatalytic degradation of leather dye, acid green 16 using ZnO in the slurry and thin film forms. Indian Journal of Chemical Technology, 6(3), 161-165. 

Triphenylmethane dyes are usually prepared in two steps 1) condensation of an N,N-dialkylaniline with a benzaldehyde compound and 2) oxidation of the resultant leuco base (27). The synthesis of C.I. Basic Green 4 (Malachite Green) is given as an example in Fig. 13.106. Alternatively, C.I. Acid Green 50 is prepared in three steps 1) condensation of... 

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