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Reactivity of 5-nitro-2,1-benzothiazole-3-diazonium hydrogensulfate towards OH and CH acids: structure, properties, tautomerism
Authors: Macháček Vladimír | Horáková Eva
Year: 2017
Type of publication: ostatní - přednáška nebo poster
Page from-to: nestránkováno
Titles:
Language Name Abstract Keywords
eng Reactivity of 5-nitro-2,1-benzothiazole-3-diazonium hydrogensulfate towards OH and CH acids: structure, properties, tautomerism Heteroaromatic precursors of azo dyes, especially azo pigments, are really interesting in technology and industry. These pigments are highly stable compounds with high absorption coefficients. Commercially available pigment C. I. Disperse Blue 148 is derived from one of these precursors 5-nitro-2,1-benzothiazol-3-amine. [1] Blue azo dyes are prepared by the reaction of N,N-dialkylanilines with 5-nitro-2,1-benzothiazole-3-diazonium hydrogensulfate. [2] The reaction of very reactive 5-nitro-2,1-benzothiazole-3-diazonium hydrogensulfate with phenols or C-acids has never been described. In this work, we studied reaction of 5-nitro-2,1-benzothiazole-3-diazonium ion with various substrates (phenol, 2-naphthol, mesitylene, acetone, acetylacetone and ethyl acetoacetate). Prepared azo and hydrazo compounds were characterized by NMR, X-ray diffraction and HRMS. On the other hand, we studied acidobasic properties because spectral behavior of dyes depends on the acidity of environment and this fact is very important for their application. The compounds prepared in this work contain strong electron-withdrawing heterocyclic residuum which substantially increases the acidity of alternatively present OH, NH or CH groups. The hydrazones from aliphatic substrates are more acidic than heteroarylazo phenols. All the compounds possess very distinctive solvatochromism. [3] 5-nitro-2,1-benzothiazole-3-diazonium hydrogensulfate, acidobasic properties, tautomerism

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