Infrared and nuclear magnetic resonance properties of benzoyl derivatives of five‐membered monoheterocycles and determination of aromaticity indices

Abstract Benzophenones, 2‐benzoylthiophenes, 2‐benzoylpyrroles, and 2‐benzoylfurans, which have substituents at m ‐ and p ‐positions of the benzoyl ring were prepared and their ir and nmr spectra were obtained in 0.1 M chloroform‐ d solution. The chemical shift values of each series were plotted against the Hammett substituent parameters to give good correlation, with the exception of the ortho ‐Hs and ‐Cs. The slopes as well as the differences in chemical shift gave sets of meaningful values for the indices of aromaticy.