Sublimation enthalpies at 298.15K using correlation gas chromatography and differential scanning calorimetry measurements

Abstract

The sublimation enthalpies of 17 hydrocarbons are obtained by combining the technique of correlation gas chromatography (CGC), to evaluate vaporization enthalpies at 298.15 K, and differential scanning calorimetry (DSC) to measure fusion enthalpies. Vaporization enthalpies at 298.15 K obtained by CGC are compared to values measured directly from vapor pressure measurements at temperatures above the melting point by adjusting the experimental vaporization enthalpy for the effects of temperature. Vaporization enthalpies obtained by these two methods agree within AE3877 J mol À1 . Fusion enthalpies are similarly adjusted for temperature. Sublimation enthalpies, obtained by combining temperature adjusted fusion, and vaporization enthalpies agree within AE2580 J mol À1. The sublimation enthalpies of azulene and 1,8-cyclotetradecadiyne are also measured by head-space analysis resulting in values of 76880 and 94348 J mol À1 at 298.15 K, respectively. # 1998 Elsevier Science B.V.

The enthalpy of vaporization and sublimation of corannulene, coronene, and perylene at T= 298.15 K

“…This adjustment is clearly unrealistic and is probably a consequence of using equation (4) over a temperature range that greatly exceeds its valid limits. (12)(13)(14) Equation (4) has been tested to about T = 500 K and found to give reasonable temperature adjustments. The melting temperature for coronene is simply beyond the applicable temperature range.…”

“…The sublimation enthalpies of corannulene, coronene, and perylene have also been measured from the sum of the vaporization and fusion enthalpies adjusted for temperature to T = 298.15 K. The vaporization enthalpies of these samples have been obtained by means of correlation-gas chromatography. (5,6) The gas-phase enthalpies of formation of corannulene and perylene are evaluated, and the most probable experimental value for the enthalpy of sublimation of coronene is provided. The results are compared with theoretical calculations reported previously.…”

Enthalpies of Sublimation of Organic and Organometallic Compounds. 1910–2001

“…5,6 Our interests in sublimation enthalpies goes back nearly 3 decades. 5 Initially interested in using sublimation enthalpies to correct enthalpies of formation data to a standard state, we have since focused our attention on their measurement, 7 estimation, 8 and assessment. 9 In a parallel study, a compilation of available sublimation enthalpies was initiated in the 1980s.…”

Equilibrium parameters of a liquid—vapor system and thermodynamic characteristics of adsorption of cyclic and cage hydrocarbons in squalane

“…revealed that the values of γ i ∞ in the series of structurally similar compounds change arbitrarily. However, it turned out that in molecules of strained carbocycles (17)(18)(19) and molecules containing aromatic moieties (21,22) the val ues of γ i ∞ are the highest among the considered compounds.…”

“…The thermodynamic parameters of the solid state-vapor equilibrium for molecules of adamantane and some its oxygen containing derivatives were studied by GC. 15,17 Available data on chromatographic retention of adamantane and its derivatives mainly concern logarith mic retention indices of stationary liquid phases (SLP). [18][19][20][21][22][23][24][25] Data on the thermodynamic characteristics of adsorption (TCA) (adsorption equilibrium constants, heats and en tropy of adsorption, etc.)…”