Spectroscopic studies of some 1-phenylpyrazole derivatives

Abstract

1-Phenylpyrazoles have been studied by ultraviolet, nuclear magnetic resonance, and infrared spectroscopy. The steric effects of substituents and the position of protonation in strongly acidic media are discussed in terms of the changes observed in ultraviolet and n.m.r. absorption. A new series of 1-pentafluorophenylpyrazoles has been synthesised, and their spectra are compared with those of the parent pyrazoles. Twenty-five commonly occurring bands in the infrared spectra of 1-phenylpyrazoles are tabulated and assignments have been made.