Thermodynamic, spectroscopic, and density functional theory studies of allylaryl and prop-1-enyl aryl ethers. Part 1. Thermodynamic data of isomerization
Abstract
A chemical equilibration study of the relative thermodynamic stabilities of seventy isomeric allyl aryl ethers (a) and (Z)-prop-1-enyl aryl ethers (b) in DMSO solution has been carried out. From the variation of the equilibrium constant with temperature the Gibbs energies, enthalpies, and entropies of isomerization at 298.15 K have been evaluated. Because of their low enthalpies, the (Z)-prop-1-enyl aryl ethers are strongly favored at equilibrium, the Gibbs energies of the a→b isomerization ranging from −12 to −23 kJ mol−1. The entropy contribution is negligible in most reactions, but occasionally small positive values less than +10 J K−1 mol−1 of the entropy of isomerization are found. The equilibration studies were also extended to involve two pairs of related isomeric