Quantum Chemical Analysis of the Energetics of the anti- and gauche- Conformers of Ethanol
Ethanol displays two stable conformers, the classic anti (or trans) form and a gauche conformation in which the hydroxyl hydrogen points toward one of the methyl hydrogens. Surprisingly, the two forms have nearly equal energies, and in the vapor phase the gauche form predominates because of its twofold degeneracy. An analysis of the energetics of these conformers based on natural bond orbital analysis helps to explain the apparently anomalous near degeneracy of these conformers.
Quantum Chemical Analysis of the Energetics of the anti- and gauche- Conformers of Ethanol S. Scheiner, P.G. Seybold Struct Chem 2009 20 43-48