ERIC Number: EJ1175850
Record Type: Journal
Publication Date: 2018-Apr
Abstractor: As Provided
1-Dimensional Selective Nuclear Overhauser Effect NMR Spectroscopy to Characterize Products from a Two-Step Green Chemistry Synthesis
Hopson, Russell; Lee, Po Yin Bowie; Hess, Kathless M.
Journal of Chemical Education, v95 n4 p641-647 Apr 2018
One dimensional (1-D)[superscript 1] H and [superscript 13]C 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 [superscript 1]H 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, bromination of the aromatic ring of 4'-methylacetanilide is accomplished using Oxone and ammonium bromide in an aqueous solvent. The 1-D selective NOE method is applied to determine the regioselective product of the bromination reaction. The 1-D selective NOE experiment is readily accessible and easily implemented. Successful interpretation of the 1-D selective NOE results leaves students confident in making structural assignments that would otherwise be based solely on theory or software prediction.
Descriptors: Organic Chemistry, Spectroscopy, Undergraduate Students, Science Laboratories, Laboratory Experiments, Science Experiments, Discovery Learning, Synthesis
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Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education
Authoring Institution: N/A
Identifiers - Location: Rhode Island
Grant or Contract Numbers: N/A