Article

1999 ◽  
Vol 77 (2) ◽  
pp. 249-257
Author(s):  
Raphaël Sabbah ◽  
Safi Ider
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Triple Point ◽  
Isonicotinic Acid ◽  
Picolinic Acid ◽  
Resonance Energy ◽  
Enthalpy Of Combustion ◽  
Pyridine Derivatives ◽  
Temperature Reference ◽  
Heat Capacity Measurements

The present work is concerned with a thermodynamic study of the three carboxypyridinic acids (general formula: C6H5NO2). It was achieved using four techniques: combustion calorimetry of small amounts of substance (a few milligrams), sublimation calorimetry, heat capacity measurements by the drop method, and differential thermal analysis. From this study, it was possible to determine the enthalpies of combustion, sublimation, formation, and fusion of these compounds and their triple point temperatures; to discuss the relative stability of the three molecules and to compare it to those of other pyridine derivatives; to determine the resonance energy and to compare it to those of other pyridine derivatives; to determine the atomization enthalpies of our compounds and an enthalpy value for the bonds of the group (C-N=C); to determine the nature and the enthalpy of the intermolecular bonds.Key words: thermodynamics, calorimetry, differential thermal analysis, carboxypyridinic acids, picolinic acid, nicotinic acid, isonicotinic acid, enthalpy of combustion, of sublimation, of fusion, of formation, of inter- and intramolecular bonds, resonance energy, triple point temperature, reference material.

Energétique des liaisons inter- et intramoléculaires dans les trois isomères du benzènediamine

1997 ◽  
Vol 75 (4) ◽  
pp. 357-364 ◽  
Author(s):  
Raphaël Sabbah ◽  
Laurence Perez
Keyword(s):  
Thermal Analysis ◽  
Hydrogen Bond ◽  
Heat Capacity ◽  
Differential Thermal Analysis ◽  
Triple Point ◽  
Relative Stability ◽  
Enthalpy Of Combustion ◽  
Resonance Energies ◽  
Heat Capacity Measurements ◽  
Intramolecular Hydrogen

The present work is concerned with a thermodynamic study of the three benzenediamine (BDA) isomers (general formula: C6H8N2). It was achieved using four techniques: combustion calorimetry of small amounts of substance (a few milligrams), sublimation calorimetry, differential thermal analysis, and heat capacity measurements. From this study it was possible: to determine the enthalpies of combustion; sublimation, and fusion of these compounds as well as their triple point temperatures; to discuss the relative stability of the three molecules; to determine the experimental resonance energies and to compare them with the theoretical values; to determine the atomization enthalpies and to compare them with the values calculated from the energetical contributions previously obtained in our laboratory; to determine the intermolecular enthalpy bonds; to consider the existence of an intramolecular hydrogen bond in the ortho isomer. Keywords: benzenediamine isomers; enthalpy of combustion, of sublimation, of fusion, of inter- and intramolecular bonds.

Energétique des liaisons inter et intramoléculaires dans les trois isomères de l'aminophénol

1996 ◽  
Vol 74 (4) ◽  
pp. 500-507 ◽  
Author(s):  
Raphaël Sabbah ◽  
Meriem Gouali
Keyword(s):  
Thermal Analysis ◽  
Hydrogen Bond ◽  
Differential Thermal Analysis ◽  
Resonance Energy ◽  
Enthalpy Of Combustion ◽  
Atomization Enthalpy ◽  
Resonance Energies ◽  
Heat Capacity Measurements ◽  
Intramolecular Hydrogen ◽  
Triple Point Temperature

The prsesent work is concerned with a thermodynamic study of the three aminophenol isomers (general formula: C6H7NO). It was achieved using four techniques: combustion calorimetry of small amounts of substance (a few milligrams), sublimation calorimetry, differential thermal analysis, and heat capacity measurements. From this study, it was possible: to determine the enthalpies of combustion, sublimation, and fusion of these compounds; to discuss the relative stability of the three molecules; to determine the intermolecular enthalpy bonds; to determine the experimental resonance energies and to compare them with the theoretical values; to determine the atomization enthalpies and to compare them with the values calculated from the energetical contributions previously determined in our laboratory; to consider the existence of an intramolecular hydrogen bond in the ortho isomer. Key words: thermodynamics; thermochemistry; calorimetry; differential thermal analysis; 2-aminophenol or ortho-aminophenol; 3-aminophenol or meta-aminophenol; 4-aminophenol or para-aminophenol; enthalpy of combustion, of sublimation, of fusion, of atomization, enthalpy of inter and intramolecular bonds; hydrogen bond; resonance energy; triple point temperature.

Energetics of Intramolecular Bonds in 1H-1,2,4-Triazole and 1H-Benzotriazole

1999 ◽  
Vol 52 (4) ◽  
pp. 235 ◽  
Author(s):  
Raphaël Sabbah ◽  
Laurence Perez
Keyword(s):  
Thermal Analysis ◽  
Heat Capacity ◽  
Differential Thermal Analysis ◽  
General Formula ◽  
Triple Point ◽  
Thermodynamic Quantity ◽  
Atomization Enthalpy ◽  
A Value ◽  
Resonance Energies ◽  
Heat Capacity Measurements

This paper deals with a thermodynamic study of 1H-1,2,4-triazole and 1H-benzotriazole (general formula C2H3N3 and C6H5N3 respectively). Investigations were performed by combustion calorimetry of small amounts of substance (a few milligrams), sublimation calorimetry, differential thermal analysis and heat capacity measurements. The experimental combustion, sublimation and fusion enthalpies of the two compounds were determined as well as their triple point temperatures and are as follows: From these results, experimental resonance energies have been obtained and compared with theoretical values. The experimental atomization enthalpy of 1H-1,2,4-triazole is compatible with the calculated value. In the case of 1H-benzotriazole, it was possible to determine from this thermodynamic quantity a value of 298·4 kJ mol-1 for the N=N bond enthalpy.

Energétique des liaisons inter- et intramoléculaires dans les trois isomères de l'aminopyridine

1998 ◽  
Vol 76 (1) ◽  
pp. 18-24 ◽  
Author(s):  
Raphaël Sabbah ◽  
Maria Ermelinda da Silva Eusébio
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
General Formula ◽  
Triple Point ◽  
Relative Stability ◽  
Combustion Calorimetry ◽  
Thermodynamic Study ◽  
Enthalpy Of Combustion ◽  
Resonance Energies

The present work is concerned with a thermodynamic study of the three aminopyridine (AP) isomers (general formula: C5H6N2). It was achieved using three techniques: combustion calorimetry of small amounts of substance (a few milligrams), sublimation calorimetry, and differential thermal analysis. From this study, it was possible to determine the enthalpies of combustion, sublimation, and fusion of these compounds and their triple point temperatures; to discuss the relative stability of the three molecules; to determine the experimental resonance energies and compare them with the theoretical values; to determine the atomization enthalpies and compare them with the values calculated from the energetical contributions previously determined in our laboratory; to determine the enthalpy of the intermolecular bonds.Key words: aminopyridine isomers; enthalpy of combustion, of sublimation, of fusion, of inter- and intramolecular bonds.

Étude thermodynamique des trois isomères du dihydroxybenzène

1991 ◽  
Vol 69 (3) ◽  
pp. 481-488 ◽  
Author(s):  
R. Sabbah ◽  
E. N. L. E. Buluku
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Triple Point ◽  
Van Der Waals Interactions ◽  
Enthalpies Of Formation ◽  
Chemical Calculation ◽  
Conjugation Energy ◽  
Heat Capacity Measurements ◽  
Intramolecular Hydrogen ◽  
Enthalpies Of Sublimation

The present work is concerned with a thermodynamic study of the three isomers of dihydroxybenzene. By combustion calorimetry of small amounts of substance, sublimation calorimetry, differential thermal analysis, and heat capacity measurements, it was possible to determine the enthalpies of formation of 1,2-, 1,3-, and 1,4-dihydroxybenzene in the condensed and gaseous phases, their enthalpies of fusion and transition, and the temperature of their triple point and transition. The experimental results are used to discuss the relative stability and determine the conjugation energy of the three compounds. The values are in good agreement with the theoretical values obtained from a quantum chemical calculation. The enthalpies of atomization enabled us to determine an energy value for the intramolecular Cb—OH bond in dihydroxybenzenes and to correlate it with previous results obtained from a study of alkane-diols. The enthalpies of sublimation were discussed. An intramolecular hydrogen bond was displayed in the ortho isomer. Intermolecular hydrogen bonds associated with van der Waals interactions exist in dihydroxybenzenes. Their energy contributions were determined. Key words: thermodynamics, calorimetry, differential thermal analysis, 1,2-benzenediol or 1,2-dihydroxybenzene or catechol; 1,3-benzenediol or 1,3-dihydroxybenzeneorresorcinol; 1,4-benzenediol or 1,4-dihydroxybenzene or hydroquinone or quinol; enthalpies of combustion, of sublimation, of fusion, of transition, energy of conjugation, enthalpies of atomization, of inter- and intramolecular bonds; triple point and transition temperatures.

Étude thermodynamique de l'acridone et de la thioxanthone

1992 ◽  
Vol 70 (1) ◽  
pp. 24-28 ◽  
Author(s):  
Raphaël Sabbah ◽  
Lahcen El Watik
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Resonance Energy ◽  
Experimental Result ◽  
Thermodynamic Quantities ◽  
A Value ◽  
Experimental Enthalpy ◽  
The Difference ◽  
Heat Capacity Measurements ◽  
Triple Point Temperature

In the present work we studied acridone and thioxanthone by combustion calorimetry of small amounts of substance, by sublimation calorimetry, by differential thermal analysis, and by heat capacity measurements. The thermodynamic quantities derived are as follows: For acridone: [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text] For thioxanthone: [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text] ΔfusHm = (35.50 ± 0.28) kJ mol−1, Ttp = (487.88 ± 0.02) K. The experimental results permitted us to determine for each molecule its resonance energy and to compare it with the theoretical value. This comparison fits well for acridone, which is planar. The difference observed in the case of thioxanthone shows that this molecule is not planar, in accord with literature structural results. From the experimental enthalpy of atomization of acridone, we determined an enthalpy value for the Cb—N bond. Using the enthalpy contributions previously determined in our laboratory, we found a value for the enthalpy of atomization of thioxanthone in accord with the experimental result. Keywords: thermodynamics; calorimetry; differential thermal analysis; acridone; thioxanthone; enthalpies of combustion, of sublimation, of fusion; resonance energy; enthalpies of atomization, of intramolecular bonds; triple point temperature.

Energetics of Intra- and Inter-molecular Bonds in the Three Nitrophenols

1994 ◽  
Vol 47 (9) ◽  
pp. 1651 ◽  
Author(s):  
R Sabbah ◽  
M Gouali
Keyword(s):  
Thermal Analysis ◽  
Hydrogen Bond ◽  
Heat Capacity ◽  
Differential Thermal Analysis ◽  
Relative Stability ◽  
Intermolecular Bond ◽  
Resonance Energies ◽  
Heat Capacity Measurements ◽  
Intramolecular Hydrogen ◽  
Good Agreement

A thermodynamic study of the three nitrophenol isomers (general formula C6H5NO3) was realized by combustion calorimetry of small amounts of substance (a few milligrams), sublimation calorimetry, differential thermal analysis and heat capacity measurements. The experimental enthalpies of combustion, sublimation and fusion of these compounds are as follows: ortho para -ΔcH�m(s,298.15K)/kJ mol-1 2871.0�1.3 2875.1�0.9 2868.5�1.0 ΔsubH�m(298.15K)/kJ mol-1 72.30�0.28 91.23�0.49 92.39�0.43 ΔfusHm/kJ mol-1 18.32�0.35 20.54�0.34 17.33�0.10 Ttriple point/K 318.40�0.01 370.51�0.01 387.26�0.05   The strength of the intramolecular hydrogen bond in the ortho isomer was estimated equal to 20.09 kJ mol-1. The relative stability of the three isomers is discussed, and the intermolecular bond enthalpies have been determined. The experimental resonance energies Eexp,conj are 168.7, 142.8 and 148.2 kJ mol-1 for ortho -, meta- and para-nitrophenol respectively, and are in good agreement with theoretical values. The experimental atomization enthalpies Δa,expH°m(298.15K) are 6742.5�1.9, 6719.5�1.7 and 6724.9�1.8 kJ mol-1 for ortho -, meta- and para-nitrophenol respectively.

Étude thermodynamique des trois isomères de l'acide hydroxybenzoïque

1993 ◽  
Vol 71 (9) ◽  
pp. 1378-1383 ◽  
Author(s):  
Raphaël Sabbah ◽  
Thi Huy Duc Le
Keyword(s):  
Thermal Analysis ◽  
Heat Capacity ◽  
Differential Thermal Analysis ◽  
Thermodynamic Study ◽  
Experimental Results ◽  
Ortho Isomer ◽  
Resonance Energies ◽  
Hydroxybenzoic Acids ◽  
Heat Capacity Measurements ◽  
Good Agreement

A thermodynamic study of the three hydroxybenzoic acids was carried out by combustion and sublimation calorimetry, heat capacity measurements, and differential thermal analysis. The experimental results (in kJ mol−1) are summarized as:[Formula: see text]From these experimental results, it was possible to determine for the three isomers (i) the resonance energies. From their comparison, the ortho isomer seems to be the most stable. This result is discussed using a structural consideration; (ii) the enthalpies of atomization. These values are in good agreement with that calculated using a contribution method.

Étude thermodynamique des acides phtalique, isophtalique et téréphtalique

1999 ◽  
Vol 77 (9) ◽  
pp. 1508-1513 ◽  
Author(s):  
Raphaël Sabbah ◽  
Laurence Perez
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Resonance Energy ◽  
Intermolecular Forces ◽  
Enthalpies Of Formation ◽  
Enthalpy Of Sublimation ◽  
Gaseous State ◽  
Combustion Enthalpy ◽  
The One ◽  
Triple Point Temperature

A thermodynamic study of phthalic, isophthalic, and terephthalic acids (general formula: C8H6O4) was carried out by sublimation calorimetry and differential thermal analysis. With values of combustion enthalpy taken from the literature, it was possible to determine their enthalpies of formation in the gaseous state and at 298.15 K and their resonance energy. The results enabled us to do a comparative study of the relative stability of the three acids, on the one hand, and of different benzene disubstituted derivatives, on the other hand. From the enthalpy of sublimation, it was possible to determine the energetic contribution of the different intermolecular forces in the crystals of the three acids.Key words: thermodynamic, calorimetry, differential thermal analysis, phthalic, isophthalic, terephthalic acids, enthalpy of fusion, of sublimation, of formation, of intermolecular bonds, resonance energy, triple point temperature.

Energetics of intra- and intermolecular bonds in ω-alkanediols. III. Thermochemical study of 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol at 298.15 K

1990 ◽  
Vol 68 (5) ◽  
pp. 731-734 ◽  
Author(s):  
P. Knauth ◽  
R. Sabbah
Keyword(s):  
Thermal Analysis ◽  
Hydrogen Bond ◽  
Differential Thermal Analysis ◽  
Triple Point ◽  
Gaseous Phase ◽  
Enthalpies Of Formation ◽  
Thermochemical Study

The enthalpies of combustion and sublimation or vaporization of the title compounds were determined on milligram samples and used to derive, at 298.15 K, the enthalpies of formation in the gaseous phase and the enthalpies of atomization. The previous conclusions drawn from the investigation of the lower ω-alkanediols were confirmed: the enthalpy of a hydrogen bond in solid ω-alkanediols amounts to 27 kJ mol−1 and the intramolecular C—C and C—OH bond enthalpies to 343.2 and 819.5 kJ mol−1, respectively. The enthalpies of fusion and the triple point temperatures of the ω-alkanediols [Formula: see text] are reported and discussed. Keywords: ω-alkanediols, enthalpies of formation, triple point temperatures, differential thermal analysis, calorimetry.

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