Thermodynamic, spectroscopic, and density functional theory studies of allyl aryl and prop-1-enyl aryl ethers. Part 1. Thermodynamic data of isomerization
Thermodynamic, spectroscopic, and density functional theory studies of allyl aryl and prop-1-enyl aryl ethers. Part 1. Thermodynamic data of isomerization
作者:Esko Taskinen
DOI:10.1039/b101837j
日期:——
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 ethers with a Me substituent on C(2) of the olefinic bond. The Me substituent was
found to increase the relative thermodynamic stability of the allylic ethers by ca. 3.4 kJ mol−1.
Skin Sensitization to Eugenol and Isoeugenol in Mice: Possible Metabolic Pathways Involving <i>ortho</i>-Quinone and Quinone Methide Intermediates
作者:Franck Bertrand、David A. Basketter、David W. Roberts、Jean-Pierre Lepoittevin
DOI:10.1021/tx960087v
日期:1997.3.1
oxidation to the o-quinone which could act directly as a hapten even if we cannot exclude a reaction via its tautomeric p-quinone methide. Isoeugenol, on the other hand, could act via a mechanism not involving demethylation and for which the evidence is consistent with a direct oxidation to the p-quinone methide.