Thin Layer Chromatography of Synthetic Dyes (V)

Thin layer chromatography has been applied to the analysis of reduction products of 12 monoazo dyes (Table 2).The dyes were reduced with stannous chloride and then spotted on cellulose plate. Mixtures of methyl acetate, glacial acetic acid and water (8: 2: 5 or 9: 2: 4), chloroform, methyl alcohol and water (1: 4: 1), and benzene, methyl alcohol and water (2: 6: 1) were employed as developing solvents for the reduction products. The location of the reduction products was carried out by irradiation of ultraviolet light and by spraying such chromogenic agents as 1-naphthol-4-sulfonic acid, 1- (4-sulfophenyl) -3-methyl-5-pyrazole, phenylhydrazine-p-sulfonic acid and pyridine-2-aldehyde. 1-Naphthol-4-sulfonic acid gave good result for diazo component, and phenylhydrazine-p-sulfonic acid or pyridine-2-aldehyde for amines obtained from azo components respectively.Infrared spectra of 1-amino-2-naphthol-3, 6-disulfonic acid, 1-amino-2-naphthol-6, 8-disulfonic acid, 1-amino-2-naphthol-6-sulfonic acid, and 2-amino-1-naphthol-4-sulfonic acid produced from the monoazo dyes are shown in Figs. 1-4. The Rf values for the reduction products of monoazo dyes are summarized in Table 2.