Synthesis of Some New Azo Dyes from 6, 8-dichloro-4-hydroxyquinolin-2(1H)one: Structural Elucidation, Solvatochromism and Spectroscopic Properties

6, 8-dichloro-4-hydroxyquinolin-2(1H)-one (2) was prepared by thermal cyclocondensation reaction of N, Nʹ-bis (2,4-dichlorophenyl)malonamide (1) at 140-150°C in polyphosphoric acid in a satisfactory yield. This compound as an enol type coupling component was then coupled with diazonium salts of some aromatic amines to synthesis of azo dyes (3)-(9). The structures of the compounds were elucidated using spectral methods FT-IR, 1H NMR and UV-vis. The effects of six organic solvents (acetic acid, ethanol, chloroform, acetonitrile, dimethyl formamide and dimethyl sulfoxide), pH and substituents of the diazotizing components on the maximum absorption wavelength of the colorants were discussed and evaluated.