Thermodynamic study of anthrone, coumarin and phenazine

Abstract

Anthrone, coumarin and phenazine were studied by combustion calorimetry of small amounts of substance, sublimation calorimetry, neat capacity measurements and differential thermal analysis.The thermodynamic quantities derived at 298.15 K allowed us to determine some energy valuez related to molecular structure which enabled us to realize a comparative study for the two isomers: chromone and coumarin, and determine an enthalpy value for some intramolecular chemical bonds in the molecules studied.

Energetic effects of ether and ketone functional groups in 9,10-dihydroanthracene compound

“…Comparing the experimental value of the enthalpy of formation in the crystalline phase, at T = 298.15 K, obtained in this work, for anthrone, À(75.3 ± 2.7) kJ Á mol À1 , with the values available in the literature, summarized in table 1, it is verified that the value reported in this work is in agreement, within the associated uncertainties, with that published in the past by Sabbah et al [6,7], À(79.9 ± 2.1) kJ Á mol À1 . When compared with the value determined by Verevkin [8], À(85.0 ± 1.2) kJ Á mol À1 , it differs by $9.7 kJ Á mol À1 .…”

“…Previously, we have also detected some inconsistencies between the computational and experimental gas-phase standard molar enthalpies of formation of anthrone [4] when considering their published experimental values [6][7][8] on the calculation of D f H m ðgÞ of other compounds. For that reason, we decided to perform new experimental studies for this compound since its thermochemical parameters are crucial for the calibration of computational approaches used for the estimation of thermodynamic properties of compounds derived from anthrone.…”

“…The first experimental thermodynamic study for anthrone was carried out by Sabbah et al [6,7], which was followed by another due to Verevkin [8] devoted to aromatic ketones. Despite noticeable differences in the standard molar enthalpies of formation in the crystalline phase and in the enthalpies of sublimation determined by these two groups, the enthalpies of formation in the gaseous phase are the same within the uncertainties associated with the results.…”

“…anthrone + 2 benzene was calculated using two different experimental values of the enthalpy of formation of diphenylmethane, in the liquid state, yielding the two different values for the enthalpy of formation of gaseous anthrone -both significantly different from the experimental values of Sabbah et al [7] and Verevkin [8].…”

Towards a Complete Description of a Polymorphic Crystal: The Example of Perylene

“…The denser (Z 2) phase of phenazine has a higher melting point than the (Z 4) phase, which does not fit the requirements of an enantiotropic system. The phenazine (Z 4) phase appears to be monotropic, and this is supported by the absence of a transition in a DTA study of (Z 2) phenazine [24]. Specific heat measurements on the two phenazine polymorphs would be of great interest for further understanding of this system.…”