Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The vaporization enthalpies and liquid vapor pressures at T/K = 298.15 have been evaluated by correlation gas chromatography for the following fatty acids (?lgHm(298.15 K)/kJ*mol 1; 108*pl298/Pa): (9Z)-hexadecenoic acid (palmitoleic acid) (123.0 +- 6.4); (6900 +- 4200), (6Z)-octadecenoic acid (petroselinic acid), (131.2 +- 2.1); (1130 +- 1000), (9Z)-octadecenoic acid (oleic acid), (132.6 +- 6.6); (1010 +- 600), (5Z,8Z,11Z,14Z)-eicosatetraenoic acid (arachidonic acid), (145.3 +- 6.8); (65 +- 37), (11Z)-eicosenoic acid (gondoic acid), (143.5 +- 2.2); (118 +- 105), (4Z,7Z,10Z,13Z,16Z,19Z)-docosahexenoic acid (cervonic acid), (162.9 +- 2.3); (2.2 +- 2.0), (15Z)-tetracosenoic acid (nervonic acid), (170.6 +- 2.3), (1.0 +- 0.9); n-tetracosanoic acid (lignoceric acid), (170.7 +- 2.3); (1.1 +- 1.0), and n-hexacosanoic acid (cerotic acid, (177.2 +- 2.4); (0.25 +- 0.22). For those fatty acids that are solids at T/K = 298.15, the following fusion temperatures, fusion and sublimation enthalpies, and solid vapor pressures are also reported (Tfus/K; ?crlHm(Tfus)/kJ*mol 1; ?crgHm(298.15 K)/kJ*mol 1; 1010*pcr298/Pa): (15Z)-tetracosenoic acid (315 +- 0.3); (60.3 +- 0.5), (228.9 +- 2.4), 27; tetracosanoic acid (356.5 +- 0.2); (84.5 +- 0.5); (253 +- 3.2), 0.4, hexacosanoic acid (358.8 +- 0.3); (88.5 +- 1.0); (257.8 +- 3.5), 0.08. Vapor pressures of the solids are believed accurate within a factor of 3. Tetracosanoic acid also exhibited phase transitions: T/K = (347 and 351); (4.94 +- 0.1) kJ*mol 1. The phase transition for hexacosanoic at T/K = (354.3 +- 0.1) was not resolved from the fusion peak; the enthalpy is included in the fusion enthalpy. Equations to evaluate liquid vapor pressures for a series of saturated and unsaturated fatty acids from T/K = (298.15 to Tb) are also derived.