Microwave Absorption and Molecular Structure in Liquids. LXXVIII. Dielectric and Association Behavior of Six Isomeric Octyl Alcohols in n-Heptane Solution

Abstract

The dielectric constants and losses of six isomeric octyl alcohols at concentrations of 0.03–0.35 mole fraction in n-heptane solution at 25°C have been measured at wavelengths of 0.204, 1.23, 3.23, 9.99, 24.8, and 49.9 cm, and the so-called static dielectric constants have been measured at 575 m. For three of these alcohols at mole fraction 0.32–0.33, dielectric constant and loss measurements were also made with an RX meter at seven wavelengths from 120 to 600 cm. A new analysis of this measuring system has been carried out to obtain more accurate values of dielectric constant and loss. For those isomers in which the methyl group is attached to the same carbon atom as the hydroxyl group or to the adjacent carbon, the dielectric absorption may be characterized by two relaxation times at all the concentrations employed. The isomers containing a relatively less-shielded hydroxyl group exhibit an additional low-frequency relaxation time at the higher alcohol concentrations. In all cases, the magnitude of the shortest relaxation time, which dominates the absorption of the most dilute solutions, is only slightly concentration-dependent and is characteristic of the relaxation of an hydroxyl group about its C–O bond. The intermediate relaxation process lengthens and makes a relatively greater contribution to the dielectric absorption with increasing alcohol concentration. The low-frequency process would appear to be associated with the existence of one or more higher polymers at the higher concentrations.