Thiazole-based dyes

This volume is intended to present a comprehensive description of the chemistry of thiazole and its monocyclic derivatives, based on the chemical literature up to December, 1976. It is not concerned with polycyclic thiazoles, such as benzo- or naphthothiazole, nor with hydrogenated derivatives, such as thiazolines or thiazolidines later volumes in this series are devoted to these derivatives. The chemistry of thiamine has also been excluded from the present volume because of the enormous amount of literature corresponding to the subject and is developed in another volume. On the other hand, a discussion of selenazole and its monocyclic derivatives has been included, and particular emphasis has been given to the cyanine dyes derived from thiazolium salts. 

Research by Zerweck et al. [2] suggests that many bake dyes contain thiazole rings. It was already known that dehydrothio-p-toluidine, which can be made by sulfur baking of />-toluidinc, and primulin bases, which are formed at higher temperatures, are both thiazole derivatives. 

A thiazole 56 (0.05 mol) or a methylene base 57 (0.05 mol), a hydroxypyridone (60) (0.05 mol) and dimethylformamide (0.075 mol, 5.5 g) were heated at 90°C in acetic anhydride (20-30 mL) for about 3 h. The solid that precipitated upon cooling to room temperature was filtered off, washed thoroughly with 2 -propanol and/or aqueous ethanol until the color of the filtrate changed from violet to red and subsequently dried in a vacuum-drying cabinet at 50 °C. For physical characterization, the dyes were recrystallized from acetic anhydride, toluene or toluene-hexane mixtures. 

To produce disperse dyes having the brightness of the anthraquinone system and the color strength of the azo system, azo dyes based on heteroaromatic amines were developed.26-28 Examples are C.I. Disperse Red 145, Disperse Blue 148, Disperse Red 156, and C.I. Disperse Blue 339. These dyes employ aminated thiazoles, benzothiazoles, benzisothiazoles, and thiadiazoles in their... 

Various types of dyes are prepared from dehydrothiotoluidine. The free base or its sulfonic acid is diazotized and coupled with various naph-tholsulfonic acids such as, for example, e acid (l-naphthol-3,8-disul-fonic acid). The resulting dye is characterized by its high purity of color and can be discharged to a pure white. Such red direct dyes are sold under various names, and are usually referred to as dyes of the erika red type. (Erika Z is the combination from dehydxothioxylidine and e acid. l-Naphthol-3,6-disulfonic acid gives a very similar dye.) In addition to the true azo dyes from dehydrothiotoluidine, two other products are made which are important yellow dyes. One of these dyes is the naphthamine yellow NN (also called chloramine yellow) (Kalle), formed from dehydrothiotoluidinesulfonic acid by oxidation with sodium hypochlorite. The other is thiazole yellow or Clayton yellow, which is made by combining the diazo compound of dehydrothiotoluidinesulfonic acid with a second molecule of the same compound to form a diazoamino compound. 

The EpiOcular model uses normal human-derived epidermal keratinocytes, which form a stratified squamous epithelium morphologically similar to that found in the cornea [36]. The main endpoint evaluated is cell viability measured by dehydrogenase conversion of the vital dye MTT (3-(4,5-Dimethyl-2-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide, Thiazolyl blue EINECS number 206-069-5, CAS number 298-93-1), into a blue formazan salt that is quantitatively measured after extraction from tissues. Two different protocols exist, the EpiOcular ET50 mainly developed for the testing of surfactants and surfactant-based mixtures, and the EpiOcular Eye Irritation Test (EIT) developed for a variety of chemistries. 

PCS of the II type are the most interesting as modifiers. Many types of polymers belong to this type. Their chains contain heteroatoms N, O, S with non-distributed -electrons. Among them are polybenzimidazoles, thiazoles, thiadiazoles, polymers of hydrocyanic acid PCS with end heteroatoms - polymethynes, cyan dyes and their analogs, PCS with repeated heteroatoms in conjugated chains - polyazines, polyschiff bases, polymeric azo- and diazocompounds and so on. 

Parts 2 and 3 of the comprehensive review of the chemistry of thiazole have appearedthese include chapters on meso-ionic thiazoles and on cyanine dyes derived from thiazolium salts, and also one on selenazole and its derivatives. The chemistry of selenazole is also included in a review of selenium-nitrogen heterocycles. An account of the chemistry of thiazolidin-4-ones (which includes 2,4-diones but not rhodanine and isorhodanine) updates an earlier review. Reviews on cyclic sulphur-nitrogen compounds and on the synthesis and transformations of nitrogen- and sulphur-containing bicyclic heterocycles have appeared. More general reviews, which contain chemistry relevant to this section, cover reactions based on the onium salts of aza-aromatics, the synthesis of... 

The PNA FIT probes contain a single cyanine dye that belongs to the thiazole orange (TO) family of intercalator dyes. The dye replaces a canonical nucleobase and, thereby, serves as a fluorescent base surrogate. PNA FIT probes respond to changes of the viscosity around the environmentally sensitive TO dye. 

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... 

Boc- and Fmoc-terminated fluorescent fluorescein PNA monomer units were synthesized by means of solid-phase synthesis, and the products had photophysical properties comparable to nonmodifled fluorescein conjugates. 2-Aminopurine (2-ap) was the first fluorophore incorporated into a PNA strand for the purpose of examining PNA-DNA complexation via fluctuation in fluorescence emission. A more sophisticated sensing design was introduced by Seitz et al. that utilized the intercalator dye thiazole orange, termed a forced intercalation probe (FIT probe), for the determination of base pair mismatches within a duplex. ... 

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