Other Cationic Basic Dyes

The triarylmethane dyes were also very important leather dyes in the past. The central carbon is sp2-hybridized (triarylmethine) and can add a hydroxyl group to form the respective carbinol base with spP-hybridized carbon. The dyes react like Lewis acids and some species act as pH indicators (e g., phenolphthaleine). The term cationic dyes is therefore recommended for this dye class instead of basic dyes. Nowadays only the sulfonated triphenylmethine dyes are used for leather. 

Basic dyes are used almost exclusively for overdyeing, e g., to achieve deep black shades by laking. Recent research indicates that new cationized sulfur dyes for leather will shortly become commercial products. In the 1970s dicationic azo dyes for paper were introduced by azo coupling of aromatic diazonium ions with heterocylic components. The resulting cationic azo dyes are also applied on leather e.g. C.I. Basic Black 11. The constitution is not disclosed. 

These are, with the exception of some metal complexes, low molecular weight wool dyes that usually have monoazo, disazo, or simple anthraquinone systems. They exhaust from a strongly acid to more neutral bath. The relatively small mol- 

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Synthetic dyes are mainly aromatic organic compounds, and they can be classified as cationic (basic dyes), anionic (direct, acid, and reactive dyes), or nonionic (disperse dyes) type [134]. Synthetic dyes are mainly used in the textile industries, but they have many other applications such as in printing, leather, papermaking, drug, and food industries [85]. Total world colorant production is estimated to be... 

Yoracryl. [Yorkshire Pat-Chem] Cationic basic dyes for acrylic, modified acrylic, and other fibers. 

Statistics for the production of basic dyes include those products hsted as cationic dyes, eg, cyanines, for dyeing polyacrylonitrile fibers and the classical triaryhnethane dyes, eg, malachite green, for coloring paper and other office apphcations (2,53). Moreover, statistics for triaryhnethane dyes are also hidden in the production figures for acid, solvent, mordant, and food dyes, and also organic pigments. Between 1975 and 1984, the aimual production of basic dyes in the United States varied from 5000—7700 t. However, from 1985—1990, aimual production of basic dyes varied from 5000—5700 t, and the annual sales value increased from 56 to 73 million per year. 

The compatibihty value is mainly related to the affinity of the dye for the particular fiber because for basic dyes on modified acryhc fibers there is htde possibihty for migration and therefore this does not play a significant part in determining compatibihty. The rate of dyeing of a specific mixture of dyes of the same compatibihty value is not determined by the value itself. The adsorption of cationic dyes is induenced by the presence of others in the dyebath the presence of cationic retarding agents and electrolytes also induences the rate of exhaustion. It is therefore possible to have a combination of dyes with a compatibihty value 5 that under specific dyebath conditions exhausts more rapidly than a combination based on dyes of compatibihty value 3. 

The name of this structural class ( quinoline ) in the Colour Index is not ideal because quinoline derivatives feature in other related classes, such as the methine basic dyes with a quinolinium cationic group. The class is more precisely associated with quinophthalone (1.15), the characteristic chromogen derived by condensation of quinoline derivatives with phthalic anhydride. This small class of yellow compounds contributes to the disperse, acid, basic and solvent ranges of dyes. 

Derivatives of triphenylmethane were among the earliest synthetic colorants, and are still in demand where bright, intense colours are needed without the necessity for outstanding fastness to light and chemical reagents. Basic dyes of this type, as well as other cationic dyes, are suitable for dyeing conventional acrylic fibres, on which they show better fastness properties than on natural fibres. The photodegradation of triphenylmethane dyes has been reviewed [42]. 

Basic (cationic) dyes. Basic dyes are water-soluble and produce colored cations in solution. They are mostly amino and substituted amino compounds soluble in acid and made insoluble by the solution being made basic. They become attached to the fibers by formation of salt linkages (ionic bonds) with anionic groups in the fiber. They are used to dye paper, polyacrylonitrile, modified nylons, and modified polyesters. In solvents other than water, they form writing and printing inks. The principal chemical classes are triaryl methane or xanthenes. Basic brown 1 is an example of a cationic dye that is readily protonated under the pH 2 to 5 conditions of dyeing [5]. 

In conclusion, the comparison of the experimental methods (HS-GC, H NMR) shows that, with regard to the anion s interaction with alcohols, excellent correlation in the relative order of the anions is found [74, 92], which also reflects the trends for anion basicity established using solvatochromic dyes [17]. In contrast, quite diverging information on cation interactions are obtained by HS-GC and II NMR, which may be due to a lower sensitivity of HS-GC towards such interactions. Furthermore, the lack of correlation to other cation-dependent studies, e.g. ESI-MS, is still inconclusive [28],... 

In studying the adsorption of dyes and other organic salts, early investigators observed instances in which the ions were not adsorbed in equal amounts. Thus with a basic dye such as Methylene Blue, the dye (cation) was adsorbed but the chloride ion remained in solution as a salt or as hydrochloric acid. Many such adsorptions, were found to be an exchange adsorption in which the activated... 

Basic dyes are cationic materials that have high affinity (typically over 6 kcal/mol) for binding to anionic sites (typically SOb" in acrylic and certain other fibers (e.g., copolymer versions of polyester and nylon). They are usually applied by batch dyeing procedures from acidic baths at temperatures of 200-220°F, using a procedure similar to the following ... 

The separation characteristics of a considerable variety of other TLC supports were also tested using different dye mixtures (magnesia, polyamide, silylated silica, octadecyl-bonded silica, carboxymethyl cellulose, zeolite, etc.) however, these supports have not been frequently applied in practical TLC of this class of compounds. Optimization procedures such as the prisma and the simplex methods have also found application in the TLC analysis of synthetic dyes. It was established that six red synthetic dyes (C.I. 15580 C.I. 15585 C.I. 15630 C.I. 15800 C.I. 15880 C.I. 15865) can be fully separated on silica high-performance TLC (HPTLC) layers in a three-solvent system calculated by the optimization models. The theoretical plate number and the consequent separation capacity of traditional TLC can be considerably enhanced by using supports of lower particle size (about 5 fim) and a narrower particle size distribution. The application of these HPTLC layers for the analysis of basic and cationic synthetic dyes has also been reviewed. The advantages of overpressured (or forced flow) TLC include improved separation efficiency, lower detection limit, and lower solvent consumption, and they have also been exploited in the analysis of synthetic dyes. 

The nse of organic dyes makes it possible to obtain a vast range of consumer products. In textile industry direct, sulfur, reactive, and vat dyes are commonly used for dyeing. Cationic dyes have appeared recently. They have got their name because like basic dyes, and in contrast to all other water-soluble dyes they dissociate into colored... 

Serum albumin, in addition to its important osmotic function, shows specific powers of reversible combination with a large variety of molecules. These include the anions and cations of many acid and basic dyes the anions of fatty acids and alkyl sulfonic acids, of many aromatic carboxylic acids and acetylated amino acids sulfonamide derivatives many types of naphthoquinone derivatives and a variety of other compounds. All these substances show a very strong preferential tendency to combine with albumin, rather than with the other proteins of... 

R. Aspland, Application of Basic Dye Cations to Anionic Fiber Dyeing Acrylic Other Fibers with Basic 54. Dyes, A Series on Dyeing. Cpt. 12, Vol. 25, No. 6,... 

The most popular coloration method is to apply the dyes continuously, usually by padding, but printing, spray jet, and droplet appHcations are used. In order to obtain patterned effects, chemical or physical resisting agents can be appHed first, and deep and normal dyeing nylon and basic dyeable nylon blends can be used. In the latter case the basic dyeable nylon is dyed with cationic dyes. Carpets can be printed in an analogous method to other textiles and this process is more popular in Europe than the continuous appHcation techniques used in the United States. 

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). 

E. Jacobson in 1882 fused phthalic anhydride with quinoline bases obtained from coal tar, which also contained quinaldine (136). He thus received quinophthalone (137). Quinophthalone derivatives bearing sulfonic or carboxylic acid functions represent suitable anionic dyes. Derivatives carrying basic side chains containing quarternary nitrogen, on the other hand, provide cationic dyes. The compounds are used especially as disperse dyes [1]. 

Found that the anionic form of the Coomassie dye reacts primarily with arginine residues within the macro molecular protein. Coomassie dye reacts to a lesser extent with other basic amino acid residues (His, Lys) and aromatic residues (Try, Tyr, Phe) present in macromolecularproteins, but not with the free amino acids. Dye binding is attributed to van der Waals forces and hydrophobic interactions. The interference seen with bases, detergents, and other compounds can be explained by their effects upon the equilibrium between the three dye forms (cationic, neutral, anionic). 

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