VIBRATIONAL SPECTRA AND TORSIONAL BARRIERS OF ANISOLE AND SOME MONOHALOGEN DERIVATIVES

A vibrational analysis of the spectra of anisole and of the ortho, meta and para substituted fluoro, chloro and bromo derivatives has been carried out. The torsional barriers restricting rotation about the phenyl-O bond have been calculated from the torsional frequencies for the pure liquids. The barriers are consistently higher for meta derivatives than for para or ortho substituted compounds, with the exception of ortho chloro and ortho bromoanisoles. The existance of rotational isomers has been established for m-fluoro-anisole, the trans conformation being the more stable. The energy difference between the two rotamers in the liquid state was found to be 580 ± 150 cal mole. © 1969.