Effect of solvent on the Synthesis of isomeric pyrazolines by microwave irradiation and their biological study

2′-Hydroxychalcones (I) react with hydrazine hydrate in ethanol to give 3-[-5-(aryl)-3, 4-dihydro-2H-pyrazol-3-yl]-6-substituted chromen-4-ones (IV). However, chalcones (I) react with hydrazine hydrate in DMF to yield 3-[-5-(aryl)-4, 5-dihydro-2H-pyrazol-3-yl]-6-substituted chromen-4-ones (V). Acetylation of (IV) afforded (VI) & (VII) in 1: 1 & 1: 2 stichometric ratio respectively. While acetylation of (V) afforded (VIII). All these compounds were scanned for their antimicrobial study against Gram +ve and Gram-ve micro-organisms.