1-Dimensional Selective Nuclear Overhauser Effect NMR Spectroscopy To Characterize Products from a Two-Step Green Chemistry Synthesis

One dimensional (1-D) 1H and 13C NMR experiments are common tools used in undergraduate organic laboratories to characterize synthesized molecules. However, 1-D NMR spectra cannot always provide unambiguous structure determination. In research laboratories, advanced NMR spectroscopy methods are employed for structural assignments of synthesized molecules. This experiment is designed to introduce undergraduate students to the application of an advanced method of 1H NMR spectroscopy, the 1-D selective nuclear Overhauser effect (NOE) experiment, to fully characterize the structure of two compounds. The experiment features a two-step green chemistry synthesis to produce the two compounds. In the first step of the synthesis, 4-methylaniline (para-toluidine) is acetylated to form 4′-methylacetanilide (para-acetotoluidide). The 1-D selective NOE method is used to identify the two different methyl groups present in 4′-methylacetanilide and to assign the aromatic protons. For the second step of the synthesis, brom...