The microwave spectrum of α-fluoropropionic acid |
| |
Authors: | E van Zoeren BP van Eijck |
| |
Institution: | Department of Structural Chemistry, University of Utrecht, Padualaan 8, 3584 CH Utrecht, The Netherlands |
| |
Abstract: | The rotational absorption lines in the microwave spectrum of α-fluoropropionic acid were shown to originate from two different molecular conformations. The rough geometries of the two conformations could be determined from the observed dipole moments and the substitution coordinates of the carboxylic hydrogen atom. In both conformations the fluorine atom is near the plane of the carboxyl group; in the conformation with the fluorine atom trans with respect to the hydroxyl group the carboxyl group has the usual geometry, while in the cis conformation the molecule is stabilized by an internal OH?F hydrogen bond. By measuring the relative intensities of the absorption lines it was found that the cis conformer is 0.5 ± 0.2 kJ mole?1 lower in energy than the trans conformer. The barrier to internal rotation of the methyl group in the trans conformation was determined from A-E line splittings in the second excited vibrational state V3 = 13.5 ± 0.3 kJ mole?1. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |