Conformational structure and molecular spectra of N-ethylacetamide and N-isopropylacetamide

By analysis of infrared and NMR spectra, N-ethylacetamide, in the liquid state, in polar and nonpolar media, in a broad temperature and concentration range, was found to exist in the form of a single pair of equivalent mirror image conformers, with the conformational angle φ in the vicinity of ± 75 °. Similarly N-isopropylacetamide exists as a single conformer or conformer pair, the possible structures of which are discussed.