Synthesis and spectroscopic characterization of 4-carboxyl-2,6-dinitrophenylazohydroxynaphthalenes

A series of azo dyes was prepared by the reaction of 4-carboxyl-2,6-dinitrobenzene diazonium ion (CDNBD) with two naphthols and three substituted naphthalene ether derivatives. UV, IR, 1H, 13C and 2D-NMR spectroscopy as well as mass spectral analyses were used to establish the structure of the new azo dyes.α-Naphthol and its ether gave para-substituted azo dyes while β-naphthol and its ethers provided ortho-substituted dyes. Dealkylation of the naphthalene ether linkage was found to occur upon coupling with the diazonium ion, to form the corresponding naphthol in the final azo product.