INFRARED SPECTRA OF THIOUREA AND ITS INCLUSION COMPOUNDS. IV. INVESTIGATIONS ON AGGREGATIONAL STATES OF SOME CYCLOHEXANE DERIVATIVES.

Abstract

Aggregational states of cyclohexanecarboxylic acid, cyclohexanol, cyclohexanemethanol and trans-2-chlorocyclohexanol, when they were enclosed in thiourea channels were investigated by the method described in the previous papers of this series. In the case of cyclohexanecarboxylic acid, the dimer structure similar to that found in the liquid states or in solution in less polar solvents was detected. The conformation of this acid could not be determined by this technique but the equatorial form, expected from stereochemical consideration, was ascertained by some other experimental evidences. Two OH stretching bands were found in cyclohexanol-thiourea adduct, one arising from the free hydroxyl group and the other from the dimer. The dimer formation seemed to stabilize the equatorial conformation so that the tendency of increasing the axial conformation in thiourea channels was not observed in this case. The intramolecular hydrogen bond of trans-2-chlorocyclohexanol was found to persist even in the thiourea adduct.