N NMR as a General Tool to Characterize the Nitrogen-Containing Species and Monitor the Nitration Process.

The usefulness of N NMR spectroscopy was highly underestimated compared with N NMR, which usually required tedious and expensive N-labeling manipulations. It is of great significance to make the N NMR spectroscopy convenient and useful considering N nuclei's high natural abundance of 99.6%. Herein, lots of efforts have been made to generalize routine N NMR to characterize nitrogen-containing species by tuning the balance between the solubility and viscosity of the samples. Satisfactory N NMR spectra of more than 60 nitrogen-containing compounds have been recorded, and the chemical shifts and the peaks' full width at half-maxima of more than 10 nitrogen-based functionalities have been summarized. Successful monitoring of the ortho-selective nitration of aniline has been demonstrated using the N NMR protocol developed in this paper, which will help realize the visualization of nitration processes in the industry.