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G Pilcher - One of the best experts on this subject based on the ideXlab platform.

  • experimental thermochemical study of the enthalpies of formation and sublimation of isonicotinamide picolinamide nicotinamide isonicotinamiden oxide and nicotinamiden oxide the dissociation enthalpies of the n o bonds
    The Journal of Chemical Thermodynamics, 2001
    Co-Authors: Maria Ribeiro D M C Da Silva, G Pilcher, Jorge Goncalves, Susana Ferreira, Luis Silva, M J Sottomayor, William E Acree
    Abstract:

    Abstract The standard ( p  ∘   =  0.1MPa) molar enthalpies of combustion in oxygen, at T  =  298.15 K, for crystalline picolinamide (2-NH 2 COPy), nicotinamide (3-NH 2 COPy), isonicotinamide (4-NH 2 COPy), nicotinamide N -oxide (3- NH 2 COPyNO), and isonicotinamide N - oxide (4-NH 2 COPyNO) were measured by static-Bomb Calorimetry. These values were used to derive the standard molar enthalpies of formation of the crystalline compounds. The standard molar enthalpies of sublimation, at T  =  298.15 K, for the three pyridinecarboxamide isomers were measured by microCalorimetry and the standard molar enthalpies of sublimation for the two pyridinecarboxamide N -oxide compounds were measured by a mass-loss effusion technique. From the enthalpies of formation of the gaseous compounds, the molar dissociation enthalpies D m o of the (N  +  – O  −  ) covalent bonds were derived. Comparison has been made with D m o (N–O) values in pyridine N -oxide derivatives.

  • standard enthalpies of formation of 2 thenoyltrifluoroacetone and monothio 2 thenoyltrifluoroacetone by rotating Bomb Calorimetry
    The Journal of Chemical Thermodynamics, 1997
    Co-Authors: M Ribeiro A V Da Silva, Luis M N B F Santos, G Pilcher
    Abstract:

    Abstract The standard ( p °=0.1 MPa) molar enthalpies of formation of crystalline 1,1,1-trifluoro-4-(2-thienyl)-4-hydroxy-3-buten-2-one, HTTFA, and 1,1,1-trifluoro-4-(2-thienyl)-4-mercapto-3-buten-2-one, HTTFAS, at T =298.15 K were measured by rotating-Bomb Calorimetry and the standard molar enthalpies of sublimation at T =298.15 K were measured by microCalorimetry, with the following results: [Table] The results demonstrate an increase in stabilization energy of ≈(38.7±5.0) kJ·mol −1 in HTTFA compared with thiophene and that in these molecules, the intramolecular hydrogen bond energy (O–H . . . O), appears ≈20 kJ·mol −1 larger than for (S–H . . . O).

  • standard molar enthalpies of formation of nine fluorinated β diketones by rotating Bomb Calorimetry
    The Journal of Chemical Thermodynamics, 1997
    Co-Authors: Manuel Ribeiro A V Da Silva, Jorge M Goncalves, G Pilcher
    Abstract:

    Abstract The standard-enthalpies of formation of the following fluorinated β-diketones at T =298.15 K were determined from their enthalpies of combustion measured using rotating Bomb Calorimetry.    Δ f H ° m 1,1,1-Trifluoropentan-2,4-dione(1) −1034.5±2.3 1,1,1-Trifluorohexan-2,4-dione(1) −1049.4±2.4 1,1,1-Trifluoro-5-methyl-hexan-2,4-dione(1) −1095.4±2.4 1,1,1-Trifluoro-5,5-dimethyl-hexan-2,4-dione(1) −1118.0±2.6 1,1,1-Trifluoro-5-methyl-heptan-2,4-dione(1) −1105.6±2.7 1,1,1,5,5,5-Hexafluoropentan-2,4-dione(1) −1623.0±4.3 1,1,1,2,2,3,3-Heptafluoro-7,7-dimethyl-octan-4,4-dione(1) −1988.3±4.9 4,4,4-Trifluoro-1-(2-furanyl)-butan-1,3-dione(cr) −1050.8±2.6 4,4,4-Trifluoro-1-(2-naphthyl)-butan-1,3-dione(cr) −901.0±3.1 With enthalpies of vaporization and sublimation, the enthalpies of formation of these β-diketones were derived for the gaseous state in their enol and keto forms. Where applicable, the enthalpies of formation in the gaseous state correlated satisfactorily with values estimated by group additivity methods.

  • enthalpies of combustion of 2 2 6 6 tetraethylazobenzenen n dioxide 2 4 6 tri 1 1 dimethylethyl nitrosobenzene and 2 4 6 tri 1 1 dimethylethyl nitrobenzene
    The Journal of Chemical Thermodynamics, 1995
    Co-Authors: William E Acree, Simon G Bott, Sheryl A Tucker, Maria Ribeiro D M C Da Silva, M A R Matos, G Pilcher
    Abstract:

    The standard (p∘= 0.1 MPa) molar enthalpies of combustion at the temperatureT= 298.15 K were measured by static-Bomb Calorimetry for crystalline 2,2′6,6′-tetraethylazobenzeneN,N-dioxide, { 2,6-(C2H5)2C6H3N(O)·}2; 2,4,6-tri(1,1-dimethylethyl)nitrosobenzene, 2,4,6-{CH3C(CH3)2}3C6H2NO; and 2,4,6-tri(1,1-dimethylethyl)nitrobenzene, 2,4,6-{ CH3C(CH3)2}3C6H2NO2. The standard molar enthalpies of sublimation atT= 298.15 K of the tri(1,1-dimethylethyl) compounds were measured by microCalorimetry. [Table] The standard molar enthalpy of decomposition of {2,6-(C2H5)2C6H3N(O)·}2to form 2,6-(C2H5)2C6H3NO(g) atT= 298.15 K was measured by microCalorimetry: ΔdecHom/kJ·mol−1) = (200.6 ± 5.6). Application of group-additivity schemes applied to nitrosobenzene and nitrobenzene derivatives shows that 2,4,6-tri(1,1-dimethylethyl)nitrosobenzene is unstrained whereas the corresponding nitrocompound shows considerable strain in accord with an X-ray structure analysis demonstrating that steric hindrance prevents dimerization of the nitrosoderivative.

  • enthalpies of combustion of p azoxyanisole and p azoxyphenetole the dissociation enthalpy of the n o bonds enthalpies of crystal to liquid crystal transitions
    The Journal of Chemical Thermodynamics, 1993
    Co-Authors: William E Acree, Sheryl A Tucker, G Pilcher, Maria Paz I Andrade, Maria Ribeiro D M C Da Silva
    Abstract:

    Abstract The standard ( p o = 0.1 MPa) molar enthalpies of combustion at the temperature 298.15 K were measured by static-Bomb Calorimetry for p -azoxyanisole and p -azoxyphenetole, and the standard molar enthalpies of sublimation of the temperature 298.15 K were measured by microCalorimetry. [[formula]] From the standard the molar enthalpies of formation of the gaseous compounds, the molar dissociation enthalpies of the N-O bonds were derived: D (N-O)/(kJ·mol -1 ): p -azoxyanisole, 317.2±5.7; p -azoxyphenetole, 320.4±4.9. Microcalorimetric measurements were made to derive the molar enthalpies of the transitions: crystal-to-liquid: for p -azoxyanisole, (29.3±0.8) kJ·mol -1 , (1.0±0.5) kJ·mol -1 ; and for p -azoxyphenetole, (27.0±0.8) kJ·mol -1 , (1.7±0.6) kJ·mol -1 , respectively.

William E Acree - One of the best experts on this subject based on the ideXlab platform.

  • experimental and theoretical study of the dissociation enthalpy of the n o bond on 2 hydroxypyridine n oxide theoretical analysis of the energetics of the n o bond for hydroxypyrydine n oxide isomers
    The Journal of Chemical Thermodynamics, 2004
    Co-Authors: Maria Ribeiro D M C Da Silva, Agostinha M R Matos, Victor M.f. Morais, Margarida S Miranda, William E Acree
    Abstract:

    Abstract The standard ( p ∘ =0.1 MPa) molar enthalpy of formation of crystalline 2-hydroxypyridine N -oxide was measured, at T =298.15 K, by static Bomb Calorimetry and the standard molar enthalpy of sublimation, at T =298.15 K, was obtained using Calvet microCalorimetry. These values were used to derive the standard molar enthalpy of formation of 2-hydroxypyridine N -oxide in gaseous phase, and to evaluate the dissociation enthalpy of the N–O bond. Additionally, high-level density functional theory calculations using the B3LYP hybrid exchange-correlation energy functional have been performed for the three isomers of hydroxypyridine N -oxide in order to confirm the experimental trend for the dissociation enthalpy of the (N–O) bond.

  • energetics of 6 methoxyquinoline and 6 methoxyquinoline n oxide the dissociation enthalpy of the n o bond
    The Journal of Chemical Thermodynamics, 2003
    Co-Authors: Maria Ribeiro D M C Da Silva, Ana L.r. Silva, Óscar O. P. Fernandes, Luis M N B F Santos, William E Acree
    Abstract:

    Abstract The standard (p o =0.1 MPa ) molar enthalpies of formation, at T=298.15 K , were determined using static-Bomb Calorimetry for crystalline 6-methoxyquinoline N -oxide (6MeOQUINO), as −(85.6±3.7) kJ · mol −1 and liquid 6-methoxyquinoline (6MeOQUI), −(25.8±2.2) kJ · mol −1 . The standard molar enthalpies of sublimation/vaporization, at T=298.15 K , were measured by microCalorimetry and from the enthalpies of formation of the gaseous compounds, the dissociation enthalpy D m 0 of the (N + –O − ) dative covalent bond was derived, as (269.2±5.0) kJ · mol −1 .

  • experimental thermochemical study of the enthalpies of formation and sublimation of isonicotinamide picolinamide nicotinamide isonicotinamiden oxide and nicotinamiden oxide the dissociation enthalpies of the n o bonds
    The Journal of Chemical Thermodynamics, 2001
    Co-Authors: Maria Ribeiro D M C Da Silva, G Pilcher, Jorge Goncalves, Susana Ferreira, Luis Silva, M J Sottomayor, William E Acree
    Abstract:

    Abstract The standard ( p  ∘   =  0.1MPa) molar enthalpies of combustion in oxygen, at T  =  298.15 K, for crystalline picolinamide (2-NH 2 COPy), nicotinamide (3-NH 2 COPy), isonicotinamide (4-NH 2 COPy), nicotinamide N -oxide (3- NH 2 COPyNO), and isonicotinamide N - oxide (4-NH 2 COPyNO) were measured by static-Bomb Calorimetry. These values were used to derive the standard molar enthalpies of formation of the crystalline compounds. The standard molar enthalpies of sublimation, at T  =  298.15 K, for the three pyridinecarboxamide isomers were measured by microCalorimetry and the standard molar enthalpies of sublimation for the two pyridinecarboxamide N -oxide compounds were measured by a mass-loss effusion technique. From the enthalpies of formation of the gaseous compounds, the molar dissociation enthalpies D m o of the (N  +  – O  −  ) covalent bonds were derived. Comparison has been made with D m o (N–O) values in pyridine N -oxide derivatives.

  • enthalpies of combustion of 2 2 6 6 tetraethylazobenzenen n dioxide 2 4 6 tri 1 1 dimethylethyl nitrosobenzene and 2 4 6 tri 1 1 dimethylethyl nitrobenzene
    The Journal of Chemical Thermodynamics, 1995
    Co-Authors: William E Acree, Simon G Bott, Sheryl A Tucker, Maria Ribeiro D M C Da Silva, M A R Matos, G Pilcher
    Abstract:

    The standard (p∘= 0.1 MPa) molar enthalpies of combustion at the temperatureT= 298.15 K were measured by static-Bomb Calorimetry for crystalline 2,2′6,6′-tetraethylazobenzeneN,N-dioxide, { 2,6-(C2H5)2C6H3N(O)·}2; 2,4,6-tri(1,1-dimethylethyl)nitrosobenzene, 2,4,6-{CH3C(CH3)2}3C6H2NO; and 2,4,6-tri(1,1-dimethylethyl)nitrobenzene, 2,4,6-{ CH3C(CH3)2}3C6H2NO2. The standard molar enthalpies of sublimation atT= 298.15 K of the tri(1,1-dimethylethyl) compounds were measured by microCalorimetry. [Table] The standard molar enthalpy of decomposition of {2,6-(C2H5)2C6H3N(O)·}2to form 2,6-(C2H5)2C6H3NO(g) atT= 298.15 K was measured by microCalorimetry: ΔdecHom/kJ·mol−1) = (200.6 ± 5.6). Application of group-additivity schemes applied to nitrosobenzene and nitrobenzene derivatives shows that 2,4,6-tri(1,1-dimethylethyl)nitrosobenzene is unstrained whereas the corresponding nitrocompound shows considerable strain in accord with an X-ray structure analysis demonstrating that steric hindrance prevents dimerization of the nitrosoderivative.

  • enthalpies of combustion of p azoxyanisole and p azoxyphenetole the dissociation enthalpy of the n o bonds enthalpies of crystal to liquid crystal transitions
    The Journal of Chemical Thermodynamics, 1993
    Co-Authors: William E Acree, Sheryl A Tucker, G Pilcher, Maria Paz I Andrade, Maria Ribeiro D M C Da Silva
    Abstract:

    Abstract The standard ( p o = 0.1 MPa) molar enthalpies of combustion at the temperature 298.15 K were measured by static-Bomb Calorimetry for p -azoxyanisole and p -azoxyphenetole, and the standard molar enthalpies of sublimation of the temperature 298.15 K were measured by microCalorimetry. [[formula]] From the standard the molar enthalpies of formation of the gaseous compounds, the molar dissociation enthalpies of the N-O bonds were derived: D (N-O)/(kJ·mol -1 ): p -azoxyanisole, 317.2±5.7; p -azoxyphenetole, 320.4±4.9. Microcalorimetric measurements were made to derive the molar enthalpies of the transitions: crystal-to-liquid: for p -azoxyanisole, (29.3±0.8) kJ·mol -1 , (1.0±0.5) kJ·mol -1 ; and for p -azoxyphenetole, (27.0±0.8) kJ·mol -1 , (1.7±0.6) kJ·mol -1 , respectively.

Manuel Ribeiro A V Da Silva - One of the best experts on this subject based on the ideXlab platform.

  • standard molar enthalpies of formation of 2 chloroquinoline 4 chloroquinoline 6 chloroquinoline and 4 7 dichloroquinoline by rotating Bomb Calorimetry
    The Journal of Chemical Thermodynamics, 2006
    Co-Authors: Manuel Ribeiro A V Da Silva, M A R Matos, Luisa M P F Amaral
    Abstract:

    Abstract The standard (p∘ = 0.1 MPa) molar enthalpies of combustion, Δ c H m ∘ , for crystalline 2-, 4-, 6-chloroquinoline and 4,7-dichloroquinoline were determined at the temperature 298.15 K using a rotating-Bomb combustion calorimeter. The standard molar enthalpies of sublimation, Δ cr g H m ∘ , at T =  298.15 K, were determined by Calvet microCalorimetry. The results were as follows: - Δ c H m ∘ ( cr ) / ( kJ · mol - 1 ) Δ cr g H m ∘ / ( kJ · mol - 1 ) 2-Chloroquinoline 4492.5 ± 1.6 84.3 ± 2.6 4-Chloroquinoline 4508.4 ± 1.6 78.6 ± 1.7 6-Chloroquinoline 4508.2 ± 1.6 80.8 ± 1.9 4,7-Dichloroquinoline 4353.3 ± 1.3 89.5 ± 2.3 These values were used to derive the standard molar enthalpies of formation of the compounds in their crystalline and gaseous phases, respectively. The derived standard molar enthalpies of formation, in the gaseous state, are analysed in terms of enthalpic increments and interpreted in terms of molecular structure.

  • standard molar enthalpy of formation of monothiodibenzoylmethane by rotating Bomb Calorimetry
    The Journal of Chemical Thermodynamics, 2004
    Co-Authors: Manuel Ribeiro A V Da Silva, Luis M N B F Santos
    Abstract:

    Abstract The standard (p∘=0.1 MPa) molar enthalpies of formation of crystalline thianthrene and monothiodibenzoylmethane, HDBMS, at T=298.15 K were measured by rotating-Bomb Calorimetry and the standard molar enthalpies of sublimation at T=298.15 K of dibenzoylmethane (HDBMO) and monothiodibenzoylmethane (HDBMS) were measured by microCalorimetry. Δ c U m ∘ (cr)/(kJ  ·  mol−1) Δ f H m ∘ (cr)/(kJ  ·  mol−1) Δ cr g H m ∘ /(kJ  ·  mol−1) Thianthrene – 7239.1 ± 2.5 182.1 ± 3.1 HDBMS – 8203.7 ± 2.0 – 6.0 ± 2.8 125.5 ± 4.9 HDBMO 113.3 ± 4.8 From the present results it could be shown that, in these molecules, the intramolecular hydrogen bond energy (O–H⋯O), is ca. 20 kJ · mol−1 larger than for (S–H⋯O).

  • standard molar enthalpies of formation of some trichloroanilines by rotating Bomb Calorimetry
    The Journal of Chemical Thermodynamics, 2002
    Co-Authors: Manuel Ribeiro A V Da Silva, Luisa M P F Amaral, Ana Lobo I M C Ferreira
    Abstract:

    Abstract The standard ( p o  =  0.1 MPa) molar enthalpies of formation Δ f H m o , at the temperature 298.15 K, for crystalline 2,3,4-, 2,4,5-, 2,4,6- and 3,4,5-trichloroaniline were derived from the molar enthalpies of combustion Δ c H m o in oxygen using rotating Bomb combustion Calorimetry. The reaction products were CO 2 (g) , N 2 (g) , and HCl · 600H 2 O(l) . The standard molar enthalpies of sublimation Δ cr g H m o at T  =  298.15 K were measured by Calvet microCalorimetry. The results are as follows: The derived standard molar enthalpies of formation of the gaseous compounds were compared with values estimated by assuming the enthalpy increment for substitution of chlorine in aniline to be the same as for substitution into benzene.

  • standard molar enthalpies of formation of nine fluorinated β diketones by rotating Bomb Calorimetry
    The Journal of Chemical Thermodynamics, 1997
    Co-Authors: Manuel Ribeiro A V Da Silva, Jorge M Goncalves, G Pilcher
    Abstract:

    Abstract The standard-enthalpies of formation of the following fluorinated β-diketones at T =298.15 K were determined from their enthalpies of combustion measured using rotating Bomb Calorimetry.    Δ f H ° m 1,1,1-Trifluoropentan-2,4-dione(1) −1034.5±2.3 1,1,1-Trifluorohexan-2,4-dione(1) −1049.4±2.4 1,1,1-Trifluoro-5-methyl-hexan-2,4-dione(1) −1095.4±2.4 1,1,1-Trifluoro-5,5-dimethyl-hexan-2,4-dione(1) −1118.0±2.6 1,1,1-Trifluoro-5-methyl-heptan-2,4-dione(1) −1105.6±2.7 1,1,1,5,5,5-Hexafluoropentan-2,4-dione(1) −1623.0±4.3 1,1,1,2,2,3,3-Heptafluoro-7,7-dimethyl-octan-4,4-dione(1) −1988.3±4.9 4,4,4-Trifluoro-1-(2-furanyl)-butan-1,3-dione(cr) −1050.8±2.6 4,4,4-Trifluoro-1-(2-naphthyl)-butan-1,3-dione(cr) −901.0±3.1 With enthalpies of vaporization and sublimation, the enthalpies of formation of these β-diketones were derived for the gaseous state in their enol and keto forms. Where applicable, the enthalpies of formation in the gaseous state correlated satisfactorily with values estimated by group additivity methods.

  • standard enthalpies of combustion of five halogen substituted 8 hydroxyquinolines by rotating Bomb Calorimetry
    The Journal of Chemical Thermodynamics, 1995
    Co-Authors: Manuel Ribeiro A V Da Silva, Maria Luísa C.c.h. Ferrão, Adelina Alves M R O Da Silva
    Abstract:

    Abstract The standard (p°= 0.1 MPa) molar enthalpies of formation of five crystalline halogen-substituted 8-hydroxyquinolines, at the temperatureT= 298.15 K, were derived from measurements of the standard molar enthalpies of combustion in oxygen by rotating-Bomb Calorimetry. Using literature values of their standard molar enthalpies of sublimation, the standard molar enthalpies of formation, atT= 298.15 K, of the gaseous compounds were derived. These values are compared with those estimated by means of structural contributions.

Maria Ribeiro D M C Da Silva - One of the best experts on this subject based on the ideXlab platform.

  • experimental and theoretical study of the dissociation enthalpy of the n o bond on 2 hydroxypyridine n oxide theoretical analysis of the energetics of the n o bond for hydroxypyrydine n oxide isomers
    The Journal of Chemical Thermodynamics, 2004
    Co-Authors: Maria Ribeiro D M C Da Silva, Agostinha M R Matos, Victor M.f. Morais, Margarida S Miranda, William E Acree
    Abstract:

    Abstract The standard ( p ∘ =0.1 MPa) molar enthalpy of formation of crystalline 2-hydroxypyridine N -oxide was measured, at T =298.15 K, by static Bomb Calorimetry and the standard molar enthalpy of sublimation, at T =298.15 K, was obtained using Calvet microCalorimetry. These values were used to derive the standard molar enthalpy of formation of 2-hydroxypyridine N -oxide in gaseous phase, and to evaluate the dissociation enthalpy of the N–O bond. Additionally, high-level density functional theory calculations using the B3LYP hybrid exchange-correlation energy functional have been performed for the three isomers of hydroxypyridine N -oxide in order to confirm the experimental trend for the dissociation enthalpy of the (N–O) bond.

  • energetics of 6 methoxyquinoline and 6 methoxyquinoline n oxide the dissociation enthalpy of the n o bond
    The Journal of Chemical Thermodynamics, 2003
    Co-Authors: Maria Ribeiro D M C Da Silva, Ana L.r. Silva, Óscar O. P. Fernandes, Luis M N B F Santos, William E Acree
    Abstract:

    Abstract The standard (p o =0.1 MPa ) molar enthalpies of formation, at T=298.15 K , were determined using static-Bomb Calorimetry for crystalline 6-methoxyquinoline N -oxide (6MeOQUINO), as −(85.6±3.7) kJ · mol −1 and liquid 6-methoxyquinoline (6MeOQUI), −(25.8±2.2) kJ · mol −1 . The standard molar enthalpies of sublimation/vaporization, at T=298.15 K , were measured by microCalorimetry and from the enthalpies of formation of the gaseous compounds, the dissociation enthalpy D m 0 of the (N + –O − ) dative covalent bond was derived, as (269.2±5.0) kJ · mol −1 .

  • experimental thermochemical study of the enthalpies of formation and sublimation of isonicotinamide picolinamide nicotinamide isonicotinamiden oxide and nicotinamiden oxide the dissociation enthalpies of the n o bonds
    The Journal of Chemical Thermodynamics, 2001
    Co-Authors: Maria Ribeiro D M C Da Silva, G Pilcher, Jorge Goncalves, Susana Ferreira, Luis Silva, M J Sottomayor, William E Acree
    Abstract:

    Abstract The standard ( p  ∘   =  0.1MPa) molar enthalpies of combustion in oxygen, at T  =  298.15 K, for crystalline picolinamide (2-NH 2 COPy), nicotinamide (3-NH 2 COPy), isonicotinamide (4-NH 2 COPy), nicotinamide N -oxide (3- NH 2 COPyNO), and isonicotinamide N - oxide (4-NH 2 COPyNO) were measured by static-Bomb Calorimetry. These values were used to derive the standard molar enthalpies of formation of the crystalline compounds. The standard molar enthalpies of sublimation, at T  =  298.15 K, for the three pyridinecarboxamide isomers were measured by microCalorimetry and the standard molar enthalpies of sublimation for the two pyridinecarboxamide N -oxide compounds were measured by a mass-loss effusion technique. From the enthalpies of formation of the gaseous compounds, the molar dissociation enthalpies D m o of the (N  +  – O  −  ) covalent bonds were derived. Comparison has been made with D m o (N–O) values in pyridine N -oxide derivatives.

  • enthalpies of combustion of 2 2 6 6 tetraethylazobenzenen n dioxide 2 4 6 tri 1 1 dimethylethyl nitrosobenzene and 2 4 6 tri 1 1 dimethylethyl nitrobenzene
    The Journal of Chemical Thermodynamics, 1995
    Co-Authors: William E Acree, Simon G Bott, Sheryl A Tucker, Maria Ribeiro D M C Da Silva, M A R Matos, G Pilcher
    Abstract:

    The standard (p∘= 0.1 MPa) molar enthalpies of combustion at the temperatureT= 298.15 K were measured by static-Bomb Calorimetry for crystalline 2,2′6,6′-tetraethylazobenzeneN,N-dioxide, { 2,6-(C2H5)2C6H3N(O)·}2; 2,4,6-tri(1,1-dimethylethyl)nitrosobenzene, 2,4,6-{CH3C(CH3)2}3C6H2NO; and 2,4,6-tri(1,1-dimethylethyl)nitrobenzene, 2,4,6-{ CH3C(CH3)2}3C6H2NO2. The standard molar enthalpies of sublimation atT= 298.15 K of the tri(1,1-dimethylethyl) compounds were measured by microCalorimetry. [Table] The standard molar enthalpy of decomposition of {2,6-(C2H5)2C6H3N(O)·}2to form 2,6-(C2H5)2C6H3NO(g) atT= 298.15 K was measured by microCalorimetry: ΔdecHom/kJ·mol−1) = (200.6 ± 5.6). Application of group-additivity schemes applied to nitrosobenzene and nitrobenzene derivatives shows that 2,4,6-tri(1,1-dimethylethyl)nitrosobenzene is unstrained whereas the corresponding nitrocompound shows considerable strain in accord with an X-ray structure analysis demonstrating that steric hindrance prevents dimerization of the nitrosoderivative.

  • enthalpies of combustion of p azoxyanisole and p azoxyphenetole the dissociation enthalpy of the n o bonds enthalpies of crystal to liquid crystal transitions
    The Journal of Chemical Thermodynamics, 1993
    Co-Authors: William E Acree, Sheryl A Tucker, G Pilcher, Maria Paz I Andrade, Maria Ribeiro D M C Da Silva
    Abstract:

    Abstract The standard ( p o = 0.1 MPa) molar enthalpies of combustion at the temperature 298.15 K were measured by static-Bomb Calorimetry for p -azoxyanisole and p -azoxyphenetole, and the standard molar enthalpies of sublimation of the temperature 298.15 K were measured by microCalorimetry. [[formula]] From the standard the molar enthalpies of formation of the gaseous compounds, the molar dissociation enthalpies of the N-O bonds were derived: D (N-O)/(kJ·mol -1 ): p -azoxyanisole, 317.2±5.7; p -azoxyphenetole, 320.4±4.9. Microcalorimetric measurements were made to derive the molar enthalpies of the transitions: crystal-to-liquid: for p -azoxyanisole, (29.3±0.8) kJ·mol -1 , (1.0±0.5) kJ·mol -1 ; and for p -azoxyphenetole, (27.0±0.8) kJ·mol -1 , (1.7±0.6) kJ·mol -1 , respectively.

Sheryl A Tucker - One of the best experts on this subject based on the ideXlab platform.

  • enthalpies of combustion of 2 2 6 6 tetraethylazobenzenen n dioxide 2 4 6 tri 1 1 dimethylethyl nitrosobenzene and 2 4 6 tri 1 1 dimethylethyl nitrobenzene
    The Journal of Chemical Thermodynamics, 1995
    Co-Authors: William E Acree, Simon G Bott, Sheryl A Tucker, Maria Ribeiro D M C Da Silva, M A R Matos, G Pilcher
    Abstract:

    The standard (p∘= 0.1 MPa) molar enthalpies of combustion at the temperatureT= 298.15 K were measured by static-Bomb Calorimetry for crystalline 2,2′6,6′-tetraethylazobenzeneN,N-dioxide, { 2,6-(C2H5)2C6H3N(O)·}2; 2,4,6-tri(1,1-dimethylethyl)nitrosobenzene, 2,4,6-{CH3C(CH3)2}3C6H2NO; and 2,4,6-tri(1,1-dimethylethyl)nitrobenzene, 2,4,6-{ CH3C(CH3)2}3C6H2NO2. The standard molar enthalpies of sublimation atT= 298.15 K of the tri(1,1-dimethylethyl) compounds were measured by microCalorimetry. [Table] The standard molar enthalpy of decomposition of {2,6-(C2H5)2C6H3N(O)·}2to form 2,6-(C2H5)2C6H3NO(g) atT= 298.15 K was measured by microCalorimetry: ΔdecHom/kJ·mol−1) = (200.6 ± 5.6). Application of group-additivity schemes applied to nitrosobenzene and nitrobenzene derivatives shows that 2,4,6-tri(1,1-dimethylethyl)nitrosobenzene is unstrained whereas the corresponding nitrocompound shows considerable strain in accord with an X-ray structure analysis demonstrating that steric hindrance prevents dimerization of the nitrosoderivative.

  • enthalpies of combustion of p azoxyanisole and p azoxyphenetole the dissociation enthalpy of the n o bonds enthalpies of crystal to liquid crystal transitions
    The Journal of Chemical Thermodynamics, 1993
    Co-Authors: William E Acree, Sheryl A Tucker, G Pilcher, Maria Paz I Andrade, Maria Ribeiro D M C Da Silva
    Abstract:

    Abstract The standard ( p o = 0.1 MPa) molar enthalpies of combustion at the temperature 298.15 K were measured by static-Bomb Calorimetry for p -azoxyanisole and p -azoxyphenetole, and the standard molar enthalpies of sublimation of the temperature 298.15 K were measured by microCalorimetry. [[formula]] From the standard the molar enthalpies of formation of the gaseous compounds, the molar dissociation enthalpies of the N-O bonds were derived: D (N-O)/(kJ·mol -1 ): p -azoxyanisole, 317.2±5.7; p -azoxyphenetole, 320.4±4.9. Microcalorimetric measurements were made to derive the molar enthalpies of the transitions: crystal-to-liquid: for p -azoxyanisole, (29.3±0.8) kJ·mol -1 , (1.0±0.5) kJ·mol -1 ; and for p -azoxyphenetole, (27.0±0.8) kJ·mol -1 , (1.7±0.6) kJ·mol -1 , respectively.

  • enthalpies of combustion of 1 4 dicyanobenzene di n oxide and 1 4 dicyanobenzene the mean dissociation enthalpy of the no bonds
    The Journal of Chemical Thermodynamics, 1992
    Co-Authors: William E Acree, Sheryl A Tucker, G Pilcher
    Abstract:

    The standard (p° = 0.1 MPa) molar enthalpies of combustion in oxygen at the temperature 298.15K were measured by static-Bomb Calorimetry for 1,4-dicyanobenzene and its di-N-oxide. The standard molar enthalpies of sublimation of these compounds were derived from vapour pressures as functions of temperature determined using Knudsen cells in a microcalorimeter.