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

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, H-1, C-13 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.

Automated summary

A series of new azo disperse dyes were synthesized by coupling different diazonium salts with 4-hydroxy-6-methyl-2H-pyran-2-one (TAL) or its derivative DHTAL. The spectroscopic data and antibacterial activity of these dyes in various solvents were investigated. Structural confirmation was done using various analytical techniques, and in vitro antibacterial activity was qualitatively and quantitatively assessed against both Gram positive and Gram negative bacteria.