Synthesis, characterization and antimicrobial activity of some new azo dyes derived from 4-hydroxy-6-methyl-2H-pyran-2-one and its dihydro derivative

Abstract A series of new azo disperse dyes was synthesized by coupling 4-hydroxy-6-methyl-2H-pyran-2-one (triacetic acid lactone, TAL) or its hydrogenated derivative 4-hydroxy-6-methyl-5,6-dihydro-2H-pyran-2-one (dihydro triacetic acid lactone, DHTAL) with diazonium salts derived from aniline, 4-bromoaniline, 4-nitroaniline, 4-methoxyaniline, 2,4-dimethoxyaniline and 2,5-dimethoxyaniline. Spectroscopic data of these dyes dissolved in five organic solvents were measured. The effects of solvent polarity, nucleophilic component and substituent nature on the visible absorption spectra of the dyes are also reported. The structures of all compounds were confirmed by FT-IR, electronic absorption in UV and visible regions, 1H, 13C and 2D NMR and high resolution mass spectroscopy (HRMS). In addition, in vitro antibacterial activity of the synthesized derivatives against Gram positive and Gram negative bacteria, both reference and clinical strains, was evaluated qualitatively and quantitatively by agar diffusion method.