Spectroscopic and acoustic studies on the rotational isomerism in 2,3-dibromo-2,3-dimethylbutane

Abstract

The vibrational spectra of 2,3-dibromo-2,3-dimethylbutane have been measured in various phases. In the liquid phase the molecule was found to exist as an equilibrium mixture of rotational isomers. A proposed frequency assignment for the gauche- and trans-isomers is given. A value of 6–7·5 kcal./mole has been estimated for the energy of activation for the gauche→trans isomerisation from acoustic measurements at ca. 50°.