Understanding the enthalpic and entropic contributions to solvent effects on osmium tetroxide complexation with pyridine

摘要

Solvent effects on the complex formation of osmium tetroxide (which is the most reliable reagent available for the cis-hydroxylation of alkenes) and pyridine were investigated using spectrophotometric techniques in different solvents (benzene, chloroform, acetone, acetonitrile, anisole, tetrahydrofuran, nitrobenzene and nitromethane). The enthalpy and entropy exhibit opposing effects on stability constant with the change in solvent. In these solvents, the entropy and enthalpy of the reaction are found to be mainly influenced by the donor number (DN) of the solvents.