Supersonic Jet Studies of Benzyl Alcohols: Minimum Energy Conformations and Torsional Motion

Supersonic jet mass resolved excitation spectroscopy is employed to determine the minimum energy conformations of benzyl alcohol and a series of nine methyl-, ethyl-, fluoro-, and aminobenzyl alcohols. The interpretation of the time-of-flight mass spectra TOFMS of these molecules leads to the assignment of specific molecular geometries for each system. The minimum energy conformation of the -CH2O moiety is determined to be perpendicular relative to the plane of the aromatic ring. The hydroxy proton in the sterically unemcumbered benzyl alcohol points toward the benzene ring. The potential energy barrier for the low frequency torsional motion of the hydroxymethyl group arises mainly from an internal hydrogen bonding interaction between the OH group and pi-system of the ring. jg