Spectroscopic studies of cyclopentyl compounds. Part III. Conformational isomerism in cyclopentanol and α-deuteriocyclopentanol

Abstract

A comprehensive temperature and solvent study has been made of the ν(OH) region of cyclopentanol. Clear evidence of a doublet is found which is interpreted as arising from the equatorial (ca. 3630 cm.^–1) and axial (3626 cm.^–1) conformers. Similar features in α-deuteriocyclopentanol are accompanied by corresponding ones in ν(C–D) at 2155 cm.^–1 for the equatorial, and 2132 cm.^–1 for the axial conformer. These ν(C–D) frequencies provide a far more definitive means of establishing conformational preferences in cycloalkyl alcohols than either the ν(C–OH) or ν(O–H) mode.