Synthesis and Spectral Properties of Hetaryl Monoazo dyes derived from 2-amino-5-nitrothiazole

Various hetarylazo dyes have been synthesized by coupling reactions between diazotised 2-amino- 5-nitrothiazole and 2-chloroaniline, 1,3-dihydroxybenzene and N-phenyl naphthylamine. Spectral measurements were carried out in different solvents. The solvatochromic behaviour of the dyes in various solvents were evaluated. The 2-amino-5-nitrothiazole dye derivatives absorb maximally at longer wavelengths and are tinctorially stronger than the 1-naphthylamine dyes, although the former dyes have higher extinction coefficients. Also, the synthesized dyes exhibit positive solvatochromism so that the absorption bands of the dye, move towards longer wavelengths as the polarity of the solvent increases.