Eco-friendly synthesis and antimicrobial activities of some 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines

Abstract

Background: Green catalyst fly ash: H 2 SO 4 was prepared by mixing fly ash and sulphuric acid. Microwave irradiations are applied for solid phase cyclization of 5-bromo-2-thienyl chalcones and phenyl hydrazine hydrate in the presence of fly ash: H 2 SO 4 yields, 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines. These pyrazolines were characterized by their physical constants and spectral data. The antimicrobial activities of all synthesized pyrazolines have been studied. Results: Scanning electron microscopy (SEM) analysis shows the morphology changes between fly ash and the catalyst fly ash: H 2 SO 4. The SEM photographs with the scale of 1 and 50 μm show the fly-ash particle is corroded by H 2 SO 4 (indicated by arrow mark), and this may be due to dissolution of fly ash by H 2 SO 4. The yields of 1-phenyl-3 (5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines is more than 75% using this catalyst under microwave heating. All pyrazolines showed moderate activities against antimicrobial strains.