Molecular acoustics. Part 8.—Conformational changes in heterocyclic molecules studied by the ultrasonic method

Abstract

Ultrasonic relaxations observed in some 2- and 4-substituted tetrahydropyrans have been attributed to the perturbation of conformational equilibria involving chair to chair inversion and also internal rotation about the exocyclic bond. In symmetrically substituted 1,3-dioxans, in which the above equilibria are inactive in ultrasonic relaxation studies, a further relaxation, associated with the equilibrium between chair and twist boat conformers, has been observed.