Infra-red spectroscopic studies of hydrogen bonding in methanol, ethanol, and t-butanol

Abstract

The infra-red spectra of methanol, ethanol and t-butanol have been investigated in the 3 μ, region (fundamental frequency of the OH stretching vibration). The alcohols were studied in CCl 4 solution over a concentration range 0.005–1.0 M and a temperature range − 15° to +60°C. Quantitative measurements of the intensity of the sharp OH band near 3630 cm −1 yielded values for the equilibrium constants and the following values for the enthalpies of dimer formation: methanol, 9.2 ± 2.5; ethanol, 7.2 ± 1.6; t-butanol, 4.8 ± 1.1 kcal/mole of dimer. Integrated intensities are given for the dimer band near 3500 cm −1 and the polymer band near 3350 cm −1. The high values of ΔH, together with the frequency shift and intensity data, suggest that the alcohol dimer is cyclic with two non-linear hydrogen bonds.