DIELECTRIC STUDY OF INTERMOLECULAR ASSOCIATION IN STERICALLY HINDERED OCTANOL ISOMERS

The equilibrium dielectric constant of 2-methyl- and 3-methyl-4-heptanol and also 2,5-dimethyl-, 2,4-dimethyl-, 2,2-dimethyl-, and 3,4-dimethyl-3-hexanol has been measured over a wide range of temperature. All isomers have closely similar dielectric behavior quantitatively as well as qualitatively. The Kirkwood correlation factor is less than unity at all temperatures in each case. The results suggest the existence of a monomer-dimer (ring) association and equilibrium constants for ring-dimer formation are deduced. ΔH° for H-bond formation in rings is estimated as -4.5 kcal/mol; ΔS° per mole of H-bond formation varies from -12 to -16 eu.