Structure elucidation of the dye Acid Red 131: complete (1)H, (13)C and (15)N NMR data assignment.

The chemistry of dyes and pigments is relevant to the textile industry, because of the importance to establish the best conditions for the finishing process and to understand the interactions among various compounds to yield the correct hue and nuances. For this reason, the molecular structure of a monoazo acid dye, C.I. Acid Red 131, was elucidated and characterized by homo- and hetero-nuclear NMR, MS, IR and UV spectroscopy techniques.