N,N-diethyl-m-toluamide (DEET) has been used in teaching laboratories as a classic example of chemical exchange that occurs between methylene (-CH2-) resonances due to restricted rotation about its amide bond. Recently, studies on analogs of DEET have shown that a third higher energy trapped conformation exists with some ortho- substitutions and is evident as a third peak in the 3.4-3.6 ppm chemical shift range on a 1D H1-NMR spectrum. Further, studies have also shown that amide bond modulation through steric interactions in combination with electronic factors have the potential to select for specific stereoisomers by altering the amide bond’s rotational activation energy. We believe that altering the size and magnitude of electron withdrawing/donating aromatic substituents in combination with cyclic amines will provide further thermodynamic insight in our quest to control molecular conformations. Cyclic amine substitutions will have alleviated steric interactions in our analogs. We will characterize higher energy conformations by 2D-NOESY and HSQC NMR experiments in addition to 1D H1-NMR. VT-NMR data will also be used to provide the basis for amide bond rotational activation energies in each one of our analogs where higher activation energies are associated with higher magnitude double bond character.

Amide bond modulation: Cyclic amines and manipulating energy landscapes for conformational preferences using DEET analogs as a model system

253rd National Meeting (2017)

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