Intramolecular OH⋯π interactions in alkenols and alkynols

Abstract

The vibrational overtone spectra of propargyl alcohol (prop-2-yn-1-ol, PA), allyl alcohol (prop-2-en-1-ol, AA), propargyl carbinol (but-3-yn-1-ol, PC) and allyl carbinol (but-3-en-1-ol, AC) were recorded with intracavity laser photoacoustic spectroscopy (ICL-PAS) in the Δv_OH = 3, 4 and 5 regions for propargyl alcohol and allyl alcohol and in the Δv_OH = 4 and 5 regions for propargyl carbinol and allyl carbinol. Local mode anharmonic oscillator calculations were performed with explicitly correlated coupled cluster methods to guide spectral assignment. Atoms in molecules (AIM) and non-covalent interactions (NCI) calculations were carried out to analyze the interactions between the OH-group and the π-electrons of the carbon–carbon multiple bonds. We ascertain the effect of the carbon chain length and saturation on the conformation and spectroscopy of the four alcohols in relation to intramolecular hydrogen bonding interactions.