6-Butyl-4-hydroxyquinolin-2-(1H)-one as an enol type coupling component for the synthesis of some new azo disperse dyes

Abstract

6-Butyl-4-hydroxyquinolin-2-(1H)-one (II) was synthesized by heating N, N′-bis (4-butylphenyl) malonamide (I) in polyphosphoric acid at 150–160°C. This compound was then coupled with ten diazotized p-substituted aniline derivatives to synthesize the corresponding azo disperse dyes 1–10 in satisfactory yields. The dyes were characterized by FT-IR, 1H NMR, UV–vis spectroscopic techniques and elemental analysis. The solvatochromism of the dyes was evaluated with respect to wavelength of maximum absorption (λmax) in six polar solvents: acetic acid, ethanol, chloroform, acetonitrile, dimethyl sulfoxide and dimethyl formamide. The effects of acid and base on the visible absorption spectra of the dyes were also reported. Spectrophotometric absorption method was used to determine ionization constants, pKa, for these dyes in 80vol.% ethanol–water medium at room temperature and the values were correlated with the substituent constant, σx, on the benzene ring.