Benzothiazole azo dye

Quatemization of a heterocyclic nitrogen atom, as in, for example, the benzothiazole azo dye (113) results in an enormous bathochromic shift from a dull red to a blue of Amax 600 nm (71LA46). Similar shifts have been observed in the quatemization of thiazoles (61C168) and clearly the shift is due to the increased attraction of electron density by the acceptor ring. 

A similar polymer containing a hetaryl-azo dye was prepared by reacting the benzothiazole azo dye 28 with the organoiron complex 27 to give complex 29 (scheme 7.9). The subsequent reaction of 29 with 4-hydroxybenzyl alcohol gave benzothiazole-containing organoiron complex 31. 

Benzothiazole, 2-amino-6-thiocyanato-azo dyes from, 1, 328 Benzothiazole, 2-aryl-synthesis, 6, 321 Benzothiazole, 2-arylamino-synthesis, 6, 323 Benzothiazole, 2-aryloxy-Fries rearrangement, 6, 289 Benzothiazole, 2-benzyl-picrate, 6, 252 Benzothiazole, 2-chloro-dyes from, 1, 321-322 synthesis, 6, 323 Benzothiazole, 2,3-dihydro-oxidation, 6, 272 Benzothiazole, 2-dimethylamino-synthesis, 5, 128... 

Systems based on the reaction of iron salts with heterocyclic hydrazines and on the oxidative coupling of 2-aminothiazoles with naphthols have also been used (64USP3129109). In a similar process a heterocyclic hydrazone, such as the benzothiazole (174), is cleaved in the presence of an oxidizing agent, and the resulting oxidation products react immediately to give an azo dye (175) (62USP3076721). 

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... 

The simplest monoazo dyes fail to meet these requirements, but by choosing intermediates known to confer substantivity and by building up the molecule to provide the necessary length and coplanarity (section 3.2.1), direct dyes can be produced from this class. Thus the highly substantive character of the benzothiazole nucleus is exploited in Cl Direct Yellow 8 (4-58), as is the alignment of the azo, ureido and acylamino groups in the substituted J acid coupling component of Cl Direct Red 65 (4-59). 

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). 

Nitro-2-R-benzothiazoles DNA damage, against Staphylococcus aureus, Bacillus subtilis [362], Euglena gracilis [363], azo disperse dyes in textile [364]... 

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