Basic yellow dyes

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. 

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). 

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. 

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. 

Yellow Dyes with Blue/Green Fluorescence. Fluorescein, C.I. Solvent Yellow 94, 45350 1 [518-45-6] (2), is perhaps the best known example, but equally important are coumarins, such as C.I. Basic Yellow40 [12221-86-2], and especially naphtha-limides such as C.I. Solvent Yellow44, 56200 [2478-20-8] (3). 

Enamine Dyes are obtained by condensation of heterocyclic methylene- a) -aldehydes with aromatic amines in an acid medium. Technically important dyes contain 1,3,3-trimethyl-2-methyleneindoline-a)-aldehyde as aldehyde component [7], C.I. Basic Yellow 11, the condensation product formed with 2,4-dimethoxyan-iline, is of particular importance (see 3.8.4). This compound dyes polyacrylonitrile a lightfast, brilliant, greenish-yellow shade. 

Zeromethine (Apocyanine) Dyes. Some representatives of the zeromethine dyes (apocyanine dyes) have been known for a long time, e.g., C.I. Basic Yellow 1, 49005 [2390-54-7] (19, Thioflavine T). 

C.I. Basic Yellow 11 [4208-80-4] (49) is included in practically all important dye ranges for dyeing polyacrylonitrile fibers. 

C.I. Basic Yellow 13 [12217-50-4] is obtained in a similar manner to Basic Yellow 11 by condensation of 4-anisidine with l,3,3-trimethyl-2-methyleneindoline-to-aldehyde. It dyes polyacrylonitrile a greener shade. 

Technical Observations. Auramine is the most important basic yellow and is highly valued because of the extraordinarily pure tints it produces. Manufacture of the dye is done in oil heated vessels, and the heating must be very carefully... 

The glacial acetic acid extract can be stained by indigo (C.I. Natural Blue 1) in a blue shade, by berberine (C.I. Natural Yellow 18), the only basic natural dye, and sometimes by madder (C.I. Natural Red 8) in a yellow shade. 

Testing of Yellow Natural Dyeings. When a yellow dyeing is boiled in glacial acetic acid (cf. solvent stripping tests), berberine (C.I. Natural Yellow 18), the only natural basic yellow, is dissolved. This dye can be identified by TLC comparison on silica gel with the solvent butanol-glacial acetic acid-water (5 1 2). 

Figure 3.20 Experimental data for dyes fitted to a Freundlich isotherm. Parameters Basic Yellow 21, a = 67, 1/ w = 0.233 Basic Blue 3, a = 79.5,1/ n = 0.231 Basic Red 22, a = 46.7,1/ n = 0.246. Data from B. Al-Duri, Y. Khader and G. McKay, ]. Chem. BiotechnoL, 53 (1992) 345. ( Society of Chemical Industry. Reproduced with permission. Permission is granted by John Wiley Sons Ltd on behalf of the SCI.

Cellulosic fibres have, for all practical purposes, no affinity for basic dyes. A few such as Auramine (C.I. basic yellow 2), Magenta (C.I. basic VIOLET 14), and Methyl Violet (C.I. basic violet 1) have some affinity for cotton, but the wet-fastness leaves very much to be desired. In the case of the protein fibre there is substantial evidence that the affinity is of a chemical nature. The reaction is essentially one of salt formation as shown ... 

The dynamic ultrafilter had been observed to retain color in spent dye solutions, but its color retention using these diluted dye filtrates (100 1) was negligible and no quantitative results are presented. A description of the experiments and preliminary results using basic yellow Cl H805H and composite filtrates has been published. ( ) Results obtained with the hyperfilter using acid yellow Cl 13906 and acid blue Cl 62055 filtrates are described here. The properties of the dye filtrates are provided in Table III. 

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