Determination of aromaticity indices of thiophene and furan by nuclear magnetic resonance spectroscopic analysis of their anilides

초록

A series of m- and p-substituted anilides of benzoic acid, 2-thienoic acid, and 2-furoic acid were prepared and their 1H and 13C nmr spectroscopic characteristics were examined. In general, good correlations were observed between the chemical shifts of proton and carbon signals of the acyl aromatic rings and the Hammett σ. Plots of the chemical shift values of the carbonyl carbons of the benzanilides against those of the 2-thienamides and 2-furamides gave an excellent correlation and the values of the slopes are 0.79 and 0.52, respectively, in dimethyl sulfoxide-d<inf>6</inf>. The slopes could be considered as a set of aromaticity index.