Solvent-free synthesis and characterization of antibacterial azo dyes in the presence of Bronsted-acid ionic liquid as a green catalyst

A convenient and efficient direct protocol for the preparation of antibacterial azo dyes by the reaction of 2-naphthol with aromatic amines in the presence of catalytic amount of N-methyl-2-pyrrolidonium hydrogen sulfate ([H-NMP]HSO4) was carried out under solvent free conditions. This method has some advantages such as: easy work-up and easy separation of catalyst from the reaction mixture. The in vitro antibacterial activities of some compounds were studied using gram positive and negative microorganisms