Crystal Structure of Strontium Laurate

Abstract

STRONTIUM soaps of even-n fatty acids from caproic to stearic were examined by X-rays ; they exhibit several crystallographic forms. Form A is obtained by precipitation from an aqueous solution of a sodium soap ; the long spacings follow a law, d = 5·879 + 2·475 N, where N is the number of carbon atoms in the corresponding fatty acid. Form B follows a law, d = 3·95 + 2·447 N ; it can generally be obtained by heating A. The forms show a certain amount of variability of their powder patterns, the causes of which are not yet known. The increment of their long spacings indicates that in both forms the hydrocarbon-chain axes are perpendicular or nearly perpendicular to the ionic sheet planes ; they differ in the structure of the ionic sheet or arrangement of the CH₃ end-groups rather than in their angle of tilt. Strontium caproate and one sample of myristate gave patterns indicating the existence of further forms.