Dielectric Absorption and D.C. Conductivity in n-primary Alcohols

Abstract

A previous publication described some electrical properties of crystalline n-primary alcohols of 16 to 26 carbon atoms. The present paper deals with an extension of the work to the lower homologues down to n-octyl alcohol, and includes the results of measurements on both the liquid and crystalline materials. To enable their more extensive investigation, the frequency range of measurement has been extended down to 10^-4 c/s. by the use of D.C. methods.The alcohols of the present series resemble the higher homologues in giving two regions of dielectric absorption which overlap to an increasing extent with decreasing molecular weight. The absorption region at lower frequencies merges with the loss due to D.C. conductivity, the latter being much larger than for other long-chain compounds so far investigated.A feature of the results is the variation in the electrical properties of different samples of the same alcohol. This may be due to variations in the relative proportions of α- and β- crystalline modifications present in different samples.The results suggest that the absorption and the D.C. conductivity both depend on the presence in the crystals of hydrogen-bond chains. The high frequency absorption appears to be related to that in secondary alcohols and is probably associated with reversal of the hydrogen-bond chains by cooperative rotation of the hydroxyl group about the C-O bonds. The latter mechanism, together with proton transition, could lead to migration of the protons, and this may account for the D.C. conductivity. The absorption at low frequencies is attributed to a Maxwell-Wagner type of mechanism resulting from the situation of the conducting hydrogen-bond chains in a non-conducting matrix.