ECO-FRIENDLY SYNTHESIS AND SPECTRAL CORRELATIONS IN SOME 1-PHENYL-3-(5-BROMOTHIOPHEN -2-YL)-5-(SUBSTITUTED PHENYL)-2-PYRAZOLINES

Abstract

A series containing eight 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazoline derivatives have been synthesized by microwave assisted, solid acidic green catalyst SiO 2 -H 3 PO 4 catalyzed cyclization of 5-bromo-2-thienyl chalcones and phenyl hydrazine hydrochloride under solvent free conditions. The yields of the pyrazolines were more than 85%. The purities of these pyrazolines were checked by their physical constant, micro analysis, Infrared, Nuclear magnetic resonance and Mass spectroscopic data published earlier in literature. From the spectral frequencies, infrared n(cm -1 ) of C=N, C-S, C-Br, 1 H and 13 C NMR chemical shifts (δ, ppm) of pyrazoline ring proton, carbon and C=N carbons were assigned and correlated with Hammett substituent constants, F and R parameters. From the results of statistical analysis the effects of substituents on the spectral frequencies have been discussed.