The
1
H-NMR spectra of all the dye compounds based on 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid show
important signals at their respective positions, confirming the
structures of various acid azo dyes, as shown in Table 1.
Methyl group protons gave a singlet between 2.14–2.20d
ppm in compoundsE1–E3, whereas in compound E6 they
appear at 2.80dppm. Methoxy group present in all the synthesized dyes showed a singlet between 3.31–3.35dppm. One of
the –OH protons from coupling component of all the dyes
appeared between 5.4–5.8dppm, further more hydroxyl group
protons present in the structure of the amine part ofE4andE5