Acrylamide Conformers: A Revision of Published Density Functional Theory Studies

Abstract

Acrylamide, with PubChem identifier CID=6579 is broadcasted to have four stable conformers contrasting with several journal publications characterizing only two or three. In this revision summary the discrepancy is clarified. Through very high precision density functional theory (DFT) calculations, three stable conformers and the three transition state barriers existing between them are verified to exist and validated with our own DFT calculations The most stable conformer is a planar molecular structure termed "sys" or "trans" in the literature. Meanwhile, a less stable structure termed "skew" pertains to two 3-dimensional structures that are energy-degenerate, but differ in their structure for being mirrored images of each other. Vibrational spectra, partial atomic charges, Cartesian coordinates, and Intrinsic Reaction Coordinate paths are summarized and recalculated with DFT at the wB97XD/Def2TZVPP level for the three stable acrylamide isomers: the sys/trans lowest in energy structure, and the two skew mirrored structures.

Figures (2)

• Figure 1: Visual depiction of the three optimized acrylamide stable conformer structures S1, S2, S3 (left) and the three calculated transition state structures between them, T12, T13, T23 (right). Calculations are done within the $\omega$B97XD/Def2TZVPP approach.
• Figure 2: The IRC within the $\omega$B97XD/Def2TZVPP approach. Left: the S1 conformer overcoming the transition state barrier T12 (or T13) and reaching the S2 (or S3) conformer. Right: the S2 (or S3) conformer overcoming the T23 energy barrier and reaching the S3 (or S2) conformer. IRC step size is 0.052918 Å.