DIELECTRIC RELAXATION IN ISOMERIC OCTYL ALCOHOLS

The dielectric constant and loss of eight isomeric octanols has been measured over a wide range of temperature and frequency. Two distinctly different types of dispersion loci are found: For those alcohols whose -OH group is so sterically hindered that association into linear chains is unfavorable, a very small, very broad dispersion, characterized by relatively short relaxation times, is found. For less hindered species, the low-frequency, relatively slow, dispersion is Debye-like, and two high-frequency dispersion regions have been resolved in two compounds. The molar activation energies for all three dispersion regions are closely similar and τ1:τ2: τ3≃100:10:l. The activation energy for the principal (Debye-like) dispersion is strongly dependent on the steric hindrance of the -OH group. Activation energies vary from about 8 to 20 kcal so that rupture of a hydrogen bond is an unlikely rate-determining step.