Thermal analysis and calorimetry of some fatty acid sodium soaps

Transition temperatures and enthalpies and some phase diagrams of pure odd and even sodium soaps have been determined by means of dif-ferential thermal analysis and scanning calorim-etry. Branched sodium soaps have been added for comparison. No essential difference has been found between the number, type, and enthalpy of the transitions of the neighboring odd and even soaps. The total enthalpy and entropy of transition are consider-ably lower than those of the corresponding par-affins and fatty acids. The entropy of the subneat-neat and perhaps of the neat isotropic transition has an alternating character, which suggests a different methyl end-group packing for even and odd soap. These two facts suggest that the melted soap is still in an organized state. Presented at the AOCS Meeting, New Orleans, May 1967.