Spectrophotometric and infra-red analyses of azo reactive dyes derived from 2-methyl-3-(2’- methylphenyl)-6-arylazo-4- oxoquinazoline

Abstract

Ultraviolet-visible and infrared spectroscopic techniques were used to determine the possible composition and functional groups present in a series of quinazoline based mono azo reactive dyes (DM_1-5) which was prepared by coupling 2-methyl-3-(2’- methylphenyl)-6-arylazo-4-oxoquinazoline diazonium solution with five (5) cyanurated coupling components . The result of visible absorption spectra showed that the λ_max obtained for each dye depends on the coupling component used and that the λ_max tend to shift to the shorter wavelength (hypsochromic shift) as the auxochromes appear to have influence on the absorption peak of the dyes... The IR spectral showed all the characteristics and representative of azo reactive dyes, with characteristic band in the range of 3400 - 3309 cm^-1 indicating the presence of -OH and –NH stretching vibration, 1382 - 1049 cm^-1 for the presence of –C-N, 1141-1010 cm^-3 for –S=0 and 925 - 56 cm^-1 for the presence of - C-Cl . The azo band occurred in the region of 1458 - 1411 cm^-1 which is due to stretching vibration of the -N=N- group. A strong band at 1643 - 1604 cm^-1 is due to the stretching vibration of -C=O group of the quinazoline compound. However, the IR spectrum did not actually reveal the chemical structure of the reactive dyes being studied. Further studies could be conducted using GCMS and NMR spectroscopy to confirm the structure of the dyes.