ULTRASOUND-ACTIVATED SYNTHESIS OF BIOACTIVE PYRAZOLONES IN WATER

Abstract: The pyrazol-3-one derivatives are synthesized by a green, efficient, and eco-friendly process through the reaction of ethyl acetoacetate with other hydrazine derivatives catalyzed by citric acid in water in ultrasonic irradiation. The cyclization is promoted by the coupling of the citric acid/H₂O system with ultrasonic technology in this solvent-free process, which provides mild reaction conditions, excellent yields, and reduced reaction times. To determine the chemical structures of the pyrazol-3-one compounds prepared, spectroscopic techniques (IR, ¹H NMR, and ¹³C NMR) were used. Antibacterial activities of the thus-obtained pyrazol-3-one derivatives were examined against various pathogenic fungi and bacteria, both Gram-positive and Gram-negative. Some of the compounds had promising antifungal and antibacterial activities, which suggests that the pyrazol-3-one template, prepared in this green way, is promising for the development of new antimicrobial drugs.