Basic yellow

PUMINESCENTMATERIALS - FLUORESCENT PIGTffiNTS pAYLIGHp] pol 15) Cl Basic Yellow 57 [68391-31-1]... 

An important advance with regard to light stabiUty was made with a group of yellow coumarin dyes with heterocycHc systems attached to the coumarin nucleus (4), eg, a greenish yellow cationic dye that is sold under the name Maxilon Brilliant Flavine 10 GFF [12221 -86-2] (Blue Wool 4), designated Cl Basic Yellow 40, available from several manufacturers. 

Mercurous Nitrate. Mercurous nitrate [10415-75-5] Hg2N20 or Hg2(N02)2, is a white monoclinic crystalline compound that is not very soluble in water but hydrolyzes to form a basic, yellow hydrate. This material is, however, soluble in cold, dilute nitric acid, and a solution is used as starting material for other water-insoluble mercurous salts. Mercurous nitrate is difficult to obtain in the pure state directly because some mercuric nitrate formation is almost unavoidable. When mercury is dissolved in hot dilute nitric acid, technical mercurous nitrate crystallizes on cooling. The use of excess mercury is helpful in reducing mercuric content, but an additional separation step is necessary. More concentrated nitric acid solutions should be avoided because these oxidize the mercurous to mercuric salt. Reagent-grade material is obtained by recrystaUization from dilute nitric acid in the presence of excess mercury. 

Diphenylmethane Dyes. The diphenyhnethane dyes aie usually classed with the tiiaiyhnethane dyes. The dyes of this subclass are ketoimine derivatives, and only three such dyes are registered in the Colour Index. They ate Auramine O [2465-27-2J Cl Basic Yellow 2 (Cl 41000) (21, R = CHg), Auramine G [2151 -60-2] Cl Basic Yellow 3 (Cl 41005) (22), and Cl Basic Yellow 37 [6358-36-7] (Cl 41001) (21, R = C2H5). These dyes are still used extensively for the coloration of paper and in the preparation of pigment lakes. 

Basic Red 22 (134), which contains 1 part ia 7 of the yellowish red 1,4-dimethyl isomer, Basic Red 29 (135), and Basic Yellow 25 (136) are all examples of delocalized cationic azo dyes. Dyes of this type can also be synthesized by Hbnig s oxidative coupling reaction of heteroaromatic hydrazones with tertiary aromatic amines. 

Azacarbocyanines. A cyanine containing three carbon atoms between heterocychc nuclei is called a carbocyanine (n = 1 in (46)). Replacing these carbon atoms by one, two, and three nitrogen atoms produces azacarbocyanines, diazacarbocyanines, and triazacarbocyanines, respectively. Dyes of these three classes are important yellow dyes for polyacrylonitrile, eg. Cl Basic Yellow 28 [52757-89-8J (Cl 48054) (47). 

Figure 12.3 Effect of thiourea on exhaustion of Cl Basic Yellow 21 (12.13) by acrylic fibres [57]...

Although treated as separate classes in the Colour Index, these structural types are closely related and the few diphenylmethane dyes such as auramine (1.28 Cl Basic Yellow 2) are now of little practical interest. Commercial usage of the triarylmethane dyes and pigments has also declined considerably in favour of the major chemical classes. They were formerly noteworthy contributors to the acid, basic, mordant and solvent ranges, primarily in the violet, blue and green sectors. Numerous structural examples are recorded in the Colour Index. The terminal groupings can be amine/quinonimine, as in auramine and crystal violet (1.29 Cl Basic Violet 3), hydroxy/quinone, or both. The aryl nuclei are not always benzenoid (section 6.5). 

It is convenient to include in this class certain tautomeric structures that can exist either in the azo form or in the alternative hydrazone form. These dyes are the diazatrimethinecyanines, which can be viewed as being derived from the trimethinecyanines (R-CH=CH-CH=R) by replacement of two of the CH units by nitrogen atoms (R-N=N-CH=R). Such dyes are important in achieving yellow and red shades and they are often most conveniently prepared by an oxidative coupling procedure using coupling components peculiar to basic dyes. Cl Basic Red 29 (4.102) and Cl Basic Yellow 24 (4.103) are typical of this group. 

The thiazole ring system is found in many types of dye. Thiazole-containing sulphur dyes and primuline were considered in section 6.4-2. Quaternised dehydrothio-p-toluidine 6.133 is available as Cl Basic Yellow 1 (6.152). Other derivatives of this intermediate are used as direct dyes, such as Cl Direct Yellow 8 (4-58). The benzothiazole ring appears in various azo disperse dyes [14], quatemisation of which gives useful cationic dyes, an important example being Cl Basic Blue 41 (4.99). Another example containing a quaternised thiazole ring is Cl Basic Red 29 (4-102). 

Of some importance as textile dyes are aza analogues of polymethine (cyanine) dyes. Azacarbocyanines result when Fischer s aldehyde is heated with primary aromatic amines. Thus Cl Basic Yellow 11 (6.220) is obtained when Fischer s aldehyde is condensed with 2,4-dimethoxyaniline. The equivalent reaction with 2-methylindoline gives Cl Basic Yellow 21 (6.221), which has superior light fastness but has been classified by ETAD as toxic [73]. The tinctorially strong golden yellow diazacarbocyanine dye Cl Basic Yellow 28 (6.222) is prepared by coupling diazotised p-anisidine with Fischer s base (6.223), followed by quaternisation with dimethyl sulphate. Some triazacarbocyanine dyes are also used commercially. 

Example Methyl orange offers a gradual end-point. Hence, two flasks containing the same volume of solution having approximately the same composition as the liquid being titrated may be prepared first, slightly acidic—Red solution, second, slightly basic—Yellow solution. 

The efficacy of diamond and metal-alloy electrodes for the degradation of the textile dyes Basic yellow 28 and Reactive black 5 was also followed by RP-HPLC. The chemical structures of the textile dyes under investigation are shown in Fig. 3.56. An ODS column (150 X 4.6 mm i.d. particle size 5 jttm) was employed for the RP-HPLC determination of... 

M. Ceron-Rivera, M.M. Davila-Jimenez and M.P. Elizalde- Gonzalez, Degradation of the textile dyes Basic yellow 28 and Reactive black 5 using diamond and metal alloys electrodes. Chemosphere, 55 (2004) 1-10. 

Several high production products for the dyeing of polyacrylonitrile textile fibres come from the azacarbocyanines class. Example in this class are the azacarbocyanine Basic Yellow 11 (2.27), synthesised from 2,4-dimethoxyaniline (2.26) and Fischer s aldehyde (2.25) the diazacarbocyanine Cl Basic Yellow 28 (2.30), synthesised from the diazonium derivative of (2.29) and Fischer s base (2.28) as shown in Figure 2.16. These dyes, although they are very bright, do tend to suffer from low fasteess to light. 

The delocalised charged dyes are dominated by cyanine dyes, exemplified by the azacarbocyanine Cl Basic Yellow 11 (2.27), the diazacarbocyanine Cl Basic Yellow 28 (2.30) and the diazahemicyanine Cl Basic Blue 41 (2.49). Where necessary quatemisation is carried out as a post colour forming reaction. Other structural types include oxazines, thiazines and triphenyhnethane dyes. 

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