Vapor pressures and vaporization enthalpy of (−) α-bisabolol and (dl) menthol by correlation gas chromatography

The vapor pressures and vaporization enthalpies of (−) α-bisabolol and ( dl )-menthol, two GRAS chemicals (generally recognized as safe) are evaluated by correlation gas chromatography using a series of saturated primary alcohols as standards. Vaporization enthalpies of (96.6 ± 2.4) and (74.2 ± 2.8) kJ mol −1  and vapor pressures of  p /Pa = (0.020 ± 0.003) and (4.5 ± 0.44) were evaluated at  T  = 298.15 K for (−) α-bisabolol and ( dl )-menthol, respectively, and compared to literature values. The vapor pressures of both compounds from  T  = (298.15 to 500) K have been derived from correlations using vapor pressures of a series of 1-alkanols and corresponding gas chromatographic retention times at 10 K intervals. The results were fit to a second order polynomial. Calculated normal boiling temperatures of  T B  = (574.8 and 492.7) K are calculated for (−) α-bisabolol and ( dl )-menthol, respectively. A normal boiling temperature of  T B  = (485.2, and 489.7) K has previously been reported for ( dl )-menthol. Vapor pressures for both ( l )-menthol and ( dl )-menthol from a previous study and ( dl )-menthol from this study are compared with literature values.