A More Challenging Interpretative Nitration Experiment Employing Substituted Benzoic Acids and Acetanilides

An experiment is described involving the nitration of ortho or meta monosubstituted benzoic acids (XC6H4CO2H, X = Halogen, Me, OH, or OMe) and monochlorinated acetanilides with nitric acid to determine the regioselectivity of addition by 1H NMR spectroscopy and molecular modeling. Students were able to interpret the 1H NMR spectra regardless of the formation of multiple products or contamination from the starting materials. With one exception, both the 1H NMR spectroscopy and computational methods agreed with the theoretical expectation and provided a nice demonstration of regioselectivity of nitration on substituted benzene.