Investigation of the OH stretching vibration of CD 3OH in CCl 4

Abstract

The OH stretching vibration of CD 3OH in CCl 4 has been investigated by FTIR spectroscopy in the concentration range 0.1 – 100 mol%. At low methanol concentrations the spectra are dominated by a relatively sharp band centred at 3644 cm −1, originating from OH oscillators not donating a hydrogen bond. The proportion of these decreases rapidly with increasing methanol concentration, and are not observable in pure methanol with the present experimental precision. Instead, a broad band envelope appears at lower wave numbers (3316 cm −1in pure CD 3OH). This band contains contributions from the various hydrogen-bonded aggregates present and is not possible to decompose into components unless additional assumptions are made. Finally, a band centred at 2790 cm −1 is present. This band has not been previously reported in the literature, probably because for CH 3OH it is obscured by the CH stretching vibrations. This band is tentatively assigned to cyclic tetramers as indicated by quantum chemical calculations.