Vibration Spectra and Rotational Isomerism of Chain Molecules. II. Butane, Pentane, Hexane, Pentane-d12, and Hexane-d14

Abstract
The Raman spectra of butane, pentane, hexane, pentane-d12, and hexane-d14 and infrared spectra of pentane-d12 and hexane-d14 were measured for the liquid and solid states. The rotational isomerism of normal paraffins was studied on the basis of the spectral observations and the normal coordinate calculations. The spectra of the deuterated compounds were useful in the confirmation of the less stable isomers and the establishment of the local symmetry force field of normal paraffins. The enthalpy differences among the rotational isomers were studied on pentane and hexane, which yielded some important data for the study of the conformations and properties of longer hydrocarbons.