Synthesis of disazo disperse dye compounds derived from 4-bromoaniline and 3-aminophenol as potential near infra-red absorbers.

Abstract

In attempt to find new near infra-red absorbing azo compounds, the synthesis and characterization of six disazo compounds are reported. The azo compounds were synthesized via diazotization of 4-bromoaniline and coupled with 3-aminophenol to afford 4-bromophenylazo-4¹-amino-2-hydroxybenzeneazo dye intermediate. This intermediate was further diazotized and coupled with various aryl-amine and phenolic couplers to give a series of disazo disperse dyes. The UV-VIS spectral properties of the dyes were evaluated and some of the dye derivatives bearing electron withdrawing groups in their couplers showed absorptions at 772nm to 786nm in the near infra-red region in dimethylformamide solution. This, in addition to their relatively high thermal stability would enhance their use as potential organic photoconductors. The results of the fastness tests of the dyes on nylon fiber and polyester fiber showed excellent sublimation, washing, good rubbing and light fastness ratings. This also indicates that the azo compounds could be of commercial importance in the textile industry. The dyes were further characterized using proton nuclear magnetic resonance (¹HNMR), carbon- 13 nuclear magnetic resonance (¹³CNMR) and infra- red (IR) analyses.

Keywords: Disazo dyes, spectral properties, disperse dyes, fastness, nylon fiber, polyesterfiber.