The Far Infrared Spectra of Monosubstituted Pyridines

Abstract

Infrared spectra in the cesium bromide region are presented for 43 monosubstituted pyridines. Two- and 3-substituted pyridines are characterized in this region by two relatively intense bands near 600 and 400 cm⁻¹. No strong characteristic bands are found for 4-substituted pyridines. The vapor-phase contours of the far infrared bands of 2-fluoro- and 2-chloropyridine indicate that the 600 and 400 cm⁻¹ bands arise, respectively, from an in-plane and an out-of-plane vibration. The pyridine spectra are compared with the spectra of some substituted benzenes