The Dielectric Properties of a Series of dl-n-Eicosanols

Abstract

Initial investigations of the dielectric properties of normal long-chain secondary alcohols were made with the symmetrical compounds because of their ready availability. The properties of long-chain polar compounds are known to vary considerably, however, with the position of the polar group in the carbon chain and it therefore seemed desirable to make dielectric measurements with some unsymmetrical alcohols. The present paper describes such an investigation of a series of dl-n-eicosanols having the hydroxyl groups in the 2-, 4-, 6-, 8-, and 10-positions, respectively. The results for the melted forms show that slight asymmetry, as in the 10-compound, has little effect on the dielectric properties, but with the more unsymmetrical 4-, 6-, and 8-compounds a considerable enhancement of the dielectric absorption is observed. This is accompanied by increased dispersion of the dielectric constant which, for the 8-compound, reaches a low frequency value of 15. Both ε" and ε' decrease during storage at room temperature. Anomalous results are obtained with dl-n-eicosan-2-ol, probably due to the molecules in the crystal lattice being alternately reversed, end-to-end. As with the symmetrical secondary alcohols, the recrystallized forms give comparatively little dielectric absorption.