Studies of Liquid-Liquid Partition Systems. V. The Formation of Mixed Dimers with Two Carboxylic Acids in Carbon Tetrachloride

The distribution of acetic, propionic and butyric acids, or of mixtures of two of these acids, between carbon tetrachloride and aqueous solutions has been studied at 25°C. The distribution data have been explained in terms of the partition of the acid monomer molecules and the dimerization of the monomer molecules in the organic phase. A salting-out effect has been observed upon additions of sodium perchlorate to the aqueous phase; this salting-out effect is larger in the order butyric>propionic>acetic acid. From the distribution data, the equilibrium constants for the distribution and the dimerization have been determined, and the formation constants for the mixed-dimer molecules have been compared with the statistical values. It has been concluded that the mixed-dimer molecules are equally stable or only a little less stable than had been statistically expected.