Dynamics and Polarity of Substituted 1,3-Dioxacyclohexanes

Abstract

The effect of substituting a hydrogen atom in the C(2) of the ring of 5-acetoxymethyl-5-ethyl-1,3-dioxacyclohexane by a phenyl group on the dynamics of the resulting compound, 2-phenyl-5-acetoxymethyl-5-ethyl-1,3-dioxacyclohexane (HEDPA), is studied. Taking the ester residue and the phenyl group to define the configuration, the 1H NMR spectrum of this compound shows that the mole ratio of cis/trans isomers is 0.70/0.30. Molecular dynamics calculations show that at room temperature the 1,3-dioxacyclohexane ring remains in the conformation used as a starting point of the MD trajectory during all the simulation. Calculations performed at higher temperatures (i.e., from 800 to 1200 K) allows the evaluation of lifetimes, population fractions, and interconversion energy barriers for the four conformations allowed for the cyclohexane ring. Extrapolation of both equilibrium and dynamic results to room temperature provides consistent values and allows the evaluation of the mean-squared dipole moment whose comparis...