Internal Rotation IV. The Optical Activity and Isomerization Energy of the Rotational Isomers of D-Secondary Butyl Alcohol

Abstract

The specific rotation of secondary butyl alcohol was measured in dilute solutions of cyclohexane at intervals of 5° between 20°C and 70°C inclusive. After corrections for solvent effect and change of refractive index with temperature had been made there remained a definite temperature dependence of the rotivity. Interpretation of the results on the basis of three optically active rotational isomers (two of equal energy and the third less stable) gave the rotivity of the third isomer as −21° and the sum of the other two as +21°. The heat of isomerization was found to be 803 cal. per mole. The concentrations of the three rotational isomers at 20° are calculated as 42.3 percent, 42.3 percent, and 15.3 percent.