Dye Classification

Fig. 3. Miscellaneous dyes used in cosmetics and medical devices. Dye classification (32), azo (33), anthraquinone (34), phthalocyanine (35), indigoid.

The color index (Cl) number, developed by the society of dyers and colorists, is used for dye classification. Once the chemical structure of a dye is known, a fivedigit Cl number is assigned to it. The first word is the dye classification and the second word is the hue or shade of the dye. For example, Cl Acid Yellow 36 (Cl 13065) is a yellow dye of the acid type. Additionally, a dye mixture may consist of several dyes for example, Navy 106 is composed of three reactive azo dyes remazol black B (Reactive Black 5), Remazol Red RB (Reactive Red 198), and Remazol Golden Yellow 3. 

Clarke-Othmer process Clark oxygen electrode Clary sage oil [8016-63-5] Class A direct dyes Classification of dyes Classified removal Classifiers Clathrate... 

Dyestuff Recognition Tests for Historic Fabrics. Methods have been developed specifically for identifying general dye classifications on historic textile artifacts. Procedures outlined by Rice (14) were followed in this portion of the study. 

Dye Classification Based on chemical structure or chromophore, 20-30 different groups of dyes can be discerned. Azo (monoazo, disazo, triazo, polyazo), anthraquinone, phtha-locyanine and triarylmethane dyes are quantitatively the most important groups. Other groups are diarylmethane, indigoid, azine, oxazine, thiazine, xanthene, nitro, nitroso, methine, thiazole, indamine, indophenol, lactone, aminoketone and hydroxyketone dyes and dyes of undetermined structure (stilbene and sulphur dyes). The vast array of commercial colourants is classified in terms of colour, structure and application method in the Colour Index (C.I.), which has been edited since 1924 (and revised every three months) by the Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists. Each dye is given a C.I. generic name determined by... 

Dyes are classified and discussed by structure. To aid in this identification the AATCC and The Society of Dyers and Colorists have published the Color Index. This publication details dye classifications by structure, generic name and an identifying Constitution Number. Other information listed is solubility parameters, heat and light stability and chemical resistance. Recently, the larger dye manufacturers have chosen not to disclose a great deal of information concerning new dyes. 

U.S. listed name Common names Cl No." CAS No." Dye classification Chemical structure ... 

VII. Classification and List of Thiazolocyanine Dyes TABLE 1121 A, STYRYL DYES... 

According to one classification (15,16), symmetrical dinuclear PMDs can be divided into two classes, A and B, with respect to the symmetry of the frontier molecular orbital (MO). Thus, the lowest unoccupied MO (LUMO) of class-A dyes is antisymmetrical and the highest occupied MO (HOMO) is symmetrical, and the TT-system contains an odd number of TT-electron pairs. On the other hand, the frontier MO symmetry of class-B dyes is the opposite, and the molecule has an even number of TT-electron pairs. 

The range of colors covers all hue classification groups except a tme red. As a rule, the hues are dull compared with other dye classes. Black is the most important, followed by blues, oHves, and browns (see Dyes and dye intermediates). 

The triaryknethane dyes are broadly classified into the triphenyknethanes (Cl 42000—43875), diphenylnaphthyknethanes (Cl 44000—44100), and miscellaneous triphenylmethane derivatives (Cl 44500—44535). The triphenyknethanes are classified further on the basis of substitution in the aromatic nuclei, as follows (/) diamino derivatives of triphenylmethane, ie, dyes of the malachite green series (Cl 42000—42175) (2) triamino derivatives of triphenylmethane, ie, dyes of the fuchsine, rosaniline, or magenta series (Cl 42500—42800) (J) aminohydroxy derivatives of triphenylmethane (Cl 43500—43570) and (4) hydroxy derivatives of triphenylmethane, ie, dyes of the rosoHc acid series (Cl 43800—43875). Monoaminotriphenyknethanes are known but they are not included in the classification because they have Httie value as dyes. 

There are three general classifications of acid dyes depending on their method of apphcation acid dyes that dye direcdy from the dyebath, mordant dyes that are capable of forming metallic lakes on the fiber when aftertreated with metallic salts, and premetallized dyes. 

Azo Dyes. The Colourindex classifications of dyes depend more on their historical eady use than on their stmctures, eg. Oil Orange is named Solvent Yellow 14, and a yellow for synthetic fibers is Disperse Yellow 23. 

Color Additives. The FDA has created a unique classification and strict limitations on color additives (see also CoLORANTS FOR FOOD, DRUGS, COSMETICS, AND MEDICAL DEVICES). Certified color additives are synthetic organic dyes that ate described in an approved color additive petition. Each manufactured lot of a certified dye must be analyzed and certified by the EDA prior to usage. Color lakes are pigments (qv) that consist of an insoluble metallic salt of a certified color additive deposited on an inert substrate. Lakes are subject to the color additive regulations of the EDA and must be certified by EDA prior to use. Noncertifted color additives requite an approved color additive petition, but individual batches need not be EDA certified prior to use. 

Acidic Heterocycles. A similar classification is made for the acidic electron-accepting terminal groups used in dipolar (merocyanine) chromophores. The unsymmetrical dyes again incorporate the -dimethylarninophenyl group, coimected to the acidic group (Fig. 3) by one or three methine carbon atoms as in the merocyanine(9), n = 0 [23517-90-0]-, n = 1 [42906-02-5]-, n = 2 [66037-49-8]-, n = 3 [66037-48-7]. 

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