Electrophilic aromatic substitution (EAS) reactions are ubiquitous in the undergraduate organic chemistry curriculum. Operationally simple EAS nitration reactions are often used in the instructional laboratory as examples of kinetically-controlled processes to predict the regiochemical outcome of the reaction via the Hammond-Leffler postulate. Herein, we present a detailed spectroscopic and computational investigation of the EAS nitration of bromobenzene in which students explore the potential energy surface via modeling of the arenium cation intermediates and determine the regiochemical outcome of the reaction by 1H-NMR and GC-MS analysis. Spectroscopic examination of the composition of the crude reaction mixture with the support of empirical 1H-NMR chemical shift parameters and computational data enables students to fully explore the product distribution of this EAS reaction.
Esselman et al. (Mon,) studied this question.