DIPOLE MOMENTS OF METALLIC SOAPS

The dipole moments of six metallic soaps, viz., the oleates of Zn Cu, Mg, Ni, Pb and Ca have been determined by a heterodyne beat method. The values Are 0.29 D, 1.20 D, 1.66 D, 2.67 D, 4.29 D and 4.49 D respectively.

Though the metallic soaps are generally regarded as non-polar from their physico-chemical, particu­larly solubility behaviour, being highly soluble in organic solvents, these data show them (except Zn) to be fairly highly polar. It is suggested that this high polarity is caused not by a high charge but by a comparatively large separation between the charges owing to the centre of negative charge residing well within the hydrccarbon radical of the oleate.

It is further observed from an examination of the μ-values of the group II elements, Mg, Ca and Zn oleates that the order of their dipole moments is opposite to the order of their ionisation potentials.

Calculation of μ-values has also been made according to a new equation developed by Jatkar, Sathe and lyengar. It is found that μ (Jatkar et. al.) is always lower than μ (Debri). It is further observed that P₂ (total polarisation) is strongly dependent on concentration both in the new and in the classical Debye equation and so the new equation does not offer any advantage over the Debye equation in these cases.

Attempts have also been made to treat the data by a recently developed simpler method of calculation due to Guggenheim. The method seems to be generally applicable and the μ-values are in fair agreement with Debye values.