Molecular acoustics. Part 4.—Volume change between conformational isomers

Abstract

By comparing ultrasonic with n.m.r. and equilibration data on conformational equilibria it has been shown that the conformers present in each of the substances 1,1,2-tribromoethane, meso-2,3-dibromobutane and 4-methyl-1,3-dioxan differ in volume by 1–3 %. This result is also consistent with density data on some cyclic compounds. This finite volume change is sufficient in many cases to invalidate an assumption used in evaluating enthalpy difference from molecular acoustic data.