Structural information from OH-stretching vibrations—XIV. The influence of local interactions on the OH-stretching frequency in alcohols with an α-triple bond

Abstract

The effect on the OH-stretching vibration of changes in the π-character of alcohols with an α-triple bond has been studied by means of the i.r. absorption band. It is demonstrated that in the investigated alcohols the OH … π interaction causes an increase of the OH-frequency as a result of the position of the OH-group with respect to that of the triple bond. Changes in the charge on the triple bond are reflected in the frequency: the larger the negative charge the higher the OH-frequency. Compared to saturated tertiary alcohols the accessibility of the hydroxyl for solvent molecules and hence the OH … solvent interaction is increased due to the absence of two (shielding) β-H-atoms. It turns out that the raising of the frequency caused by the triple bond is overruled by the lowering effect of the solvent.