Optical Anisotropy of the Molecules of the Homologues of Thallium Soaps

Abstract

The optical anisotropy of the different homologues of thallium soaps is calculated from the birefringence data reported by Pelzl and Sackmann. The negative contribution to the optical anisotropy arising from the polar groups in the “structure lamellaire” is estimated. The temperature variation of the optical anisotropy is interpreted as arising due to internal rotations about the C-C bonds of the alkyl chains of the molecule. An estimate of the barrier energy for rotation about C-C bonds is also obtained from the analysis of the data.