Structural characterization of benzoyl-1H-pyrazole derivatives obtained in lemon juice medium: Experimental and theoretical approach

Abstract

© 2019 Elsevier B.V. Simple, one-pot, and low-cost reactions of acetylacetone with a variety of substituted benzoyl hydrazides in lemon juice, as eco-friendly medium, were performed. In reactions of benzoyl hydrazides with electron-donating groups on phenyl ring, the 1-benzoyl-1H-pyrazole derivatives were obtained in short reaction time, and in good to high yields. On the other hand, benzoyl hydrazides with electron-withdrawing groups reacted slower, yielding the mixture of 1-benzoyl-5-hydroxy-4,5-dihydro-1H-pyrazole and benzoyl-1H-pyrazole derivatives. It is worth pointing out that two products, (2-chlorophenyl)(4,5-dihydro-5-hydroxy-3,5-dimethylpyrazol-1-yl)methanone and (4-iodophenyl)(3,5-dimethyl-1H-pyrazol-1-yl)methanone are reported here for the first time. All obtained compounds were characterized using IR, UV–Vis and NMR, experimentally and theoretically, as well as with melting points. Good agreement between experimental and simulated IR, UV–Vis, 1H and 13C NMR spectra was achieved. In addition, crystal structures and Hirshfeld surfaces analysis of (4,5-dihydro-5-hydroxy-3,5-dimethylpyrazol-1-yl)(4-iodophenyl)methanone were reported.