PHASE-BEHAVIOR OF BINARY MIXTURE OF PALMITOLEIC ACID (CIS-9-HEXADECENOIC ACID) AND ASCLEPIC ACID (CIS-11-OCTADECENOIC ACID)

The influence of difference in Delta chain length of cis-monounsaturated fatty acids on the phase behavior of their binary mixtures was examined based on the phase diagram of the mixture composed of palmitoleic acid (C-16;omega 7, Delta 9) and asclepic acid (C-18;omega 7, Delta 11). The phase diagram exhibited a 'eutectic-like' pattern, which demonstrates that the two components are perfectly miscible in liquid phase but much less miscible in solid phase (a-phase). This is in contrast to the case of binary mixtures composed of counter-combination of fatty acids with the same Delta- but different omega-chain length, where it was found that the molecular compounds are formed in the solid phase and the compounds are miscible with each component at least in the a: phase. The present results provide further evidence for the critical importance of the matching in Delta chain length for determining the phase behavior of cis-monounsaturated fatty acid mixtures.