双羟基杂环偶氮染料的合成及其光谱研究

Synthesis and Spectroscopic Study of Bis-hydroxy Heterocyclic Azo Dyes

分别以2-氨基苯并噻唑、2-氨基-6硝基苯并噻唑和3-氨基噻吩-2-甲酸甲酯为重氮组分,以N-苯基二乙醇胺作为偶合组分,合成了3种带有2个同等活性羟基的偶氮染料,并利用1H NMR,13C NMR,FTMS及IR对其结构进行表征.以染料b合成为例,探讨了亚硝酸钠用量和偶合pH值对产率的影响,结果发现,当亚硝酸钠和2-氨基苯并噻唑物质的量比为1.5∶1、偶合pH值为6时,合成条件较为合适.最后利用紫外光谱仪测定了染料在不同溶剂中的吸收光谱,结果表明,随着溶剂的极性增强,染料吸收波长红移;偶合组分相同情况下,苯并噻唑类偶氮染料的最大波长较噻吩类长.

Three azo dyes with two equally reactive hydroxyl groups were synthesized by coupling re- actions using 2-aminobenzothiazole, 2-amino-6-nitrobenzothiazolea and 3-thiophene-2-methyl formate as the diazo components and N-phenyl diethanolamine as the coupling component. The structures of the dyes were characterized by 1H NMR, 13C NMR, FTMS and IR. Taking the coupling reaction of 2-amino-6-nitrobenzothiazole with N-phenyl diethanolamine as an example, the effects of sodium ni- trite dosage and the pH of the reaction medium on the yield of the products were investigated. The molar ratio of sodium nitrite to 2-aminobenzothiazole is 1.5：1 and the pH of reaction medium being 6 was found to be the suitable conditions. The absorption spectra of the dyes in different solvents were determined by UV-vis. With the increase of the polarity of the solvent, the adsorption wave- length of the dyes shifted to the red range. When the azo dyes have the same coupling component, the maximum adsorption wavelength of the azo dyes with benzothiazole structure is longer than that of the dyes with thiophene structure.