Available online at www.worldscientificnews.com ( Received 11 December 2018; Accepted 26 December 2018; Date of Publication 27 December 2018 ) WSN 117 (2019) 14-28 EISSN 2392-2192 Solid acidic Bentonite/FeCl 3 catalysed solvent-free cyclization of some aryl enones: Synthesis and assessment of antimicrobial potentials of some aryl pyrazolines G. Thirunarayanan 1, *, N. Dineshkumar 1 , M. Rajarajan 2 1 Department of Chemistry, Annamalai University, Annamalainagar - 608002, India 2 Department of Chemistry, Thiruvalluvar Arts and Science College, Kurinjippadi - 607302, India *E-mail address: drgtnarayanan@gmail.com , thirunarayanan.g.10313@annamalaiuniversity.ac.in ABSTRACT Some aryl pyrazolines including 3-(substituted phenyl)-5-(naphthalen-1-yl)-1-phenyl-4,5- dihydro-1H-pyrazoles were prepared by microwave irradiation promoted cyclization of aryl enones and phenylhydrazine in the presence of solid acidic bentonite/FeCl 3 catalyst under solvent-free conditions. In this cyclization the obtained yields are more than 75%. The structural analysis of these pyrazoline derivatives were confirmed through analytical and spectral techniques. The effect of catalyst and solvent on this cyclization also investigated through the obtained yields. The antimicrobial activities of these pyrazoline derivatives were assessed through measurement of mm of zone of inhibition against their micro stains using well known Bauer-Kirby disc diffusion method. Keywords: 1,3,5-Substituted pyrazolines, Bentonite/FeCl3, Solvent-free synthesis, IR and NMR Spectra, Antimicrobial activities