The Enthalpies of Formation ofo-,m-, andp-Benzoquinone:  Gas-Phase Ion Energetics, Combustion Calorimetry, and Quantum Chemical Computations Combined

2005 ◽  
Vol 127 (16) ◽  
pp. 6116-6122 ◽  
Author(s):  
Alireza Fattahi ◽  
Steven R. Kass ◽  
Joel F. Liebman ◽  
M. Agostinha R. Matos ◽  
Margarida S. Miranda ◽  
...  
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Combustion Calorimetry ◽  
Enthalpies Of Formation ◽  
Gas Phase Ion ◽  
Quantum Chemical Computations

scholarly journals Standard Molar Enthalpies of Formation of Halomethanes Based on Quantum Chemical Computations

2020 ◽  
Author(s):  
Konstantinos Kalamatianos
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Halogen Bond ◽  
Chemical Processes ◽  
Enthalpies Of Formation ◽  
Isodesmic Reaction ◽  
Gold Standard Method ◽  
Ozone Destruction ◽  
Quantum Chemical Computations ◽  
Reaction Schemes

Accurate calculations of standard molar enthalpies of formation (ΔΗf°)m(g) and carbon-halogen bond dissociation enthalpies, BDE, of a variety of halomethanes with relevance on several atmospheric chemical processes and particularly to ozone destruction, were performed in the gas phase at 298.15 K. The (ΔΗf°)m(g) of the radicals formed through bond dissociations have also been computed. Ab initio computational methods and isodesmic reaction schemes were used. It is found that for the large majority of these species, the gold standard method of quantum chemistry (CCSD(T)) and even MP2 are capable to predict enthalpy values nearing chemical accuracy provided that isodesmic reaction schemes are used. New estimates for standard molar enthalpies of formation and BDE are suggested including for species that to our knowledge there are no experimental (ΔΗf°)m(g) (CHCl2Br, CHBr2Cl, CHBrCl, CHICl, CHIBr) or BDE values (CHCl2Br, CHBr2Cl, CHBrCl, CHICl, CHIBr) available in the literature. The method and calculational procedures presented may profitably be used to obtain accurate (ΔΗf°)m(g) and BDE values for these species.

scholarly journals Standard Molar Enthalpies of Formation of Halomethanes Based on Quantum Chemical Computations

2020 ◽  
Author(s):  
Konstantinos Kalamatianos
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Halogen Bond ◽  
Chemical Processes ◽  
Enthalpies Of Formation ◽  
Isodesmic Reaction ◽  
Gold Standard Method ◽  
Ozone Destruction ◽  
Quantum Chemical Computations ◽  
Reaction Schemes

Accurate calculations of standard molar enthalpies of formation (ΔΗf°)m(g) and carbon-halogen bond dissociation enthalpies, BDE, of a variety of halomethanes with relevance on several atmospheric chemical processes and particularly to ozone destruction, were performed in the gas phase at 298.15 K. The (ΔΗf°)m(g) of the radicals formed through bond dissociations have also been computed. Ab initio computational methods and isodesmic reaction schemes were used. It is found that for the large majority of these species, the gold standard method of quantum chemistry (CCSD(T)) and even MP2 are capable to predict enthalpy values nearing chemical accuracy provided that isodesmic reaction schemes are used. New estimates for standard molar enthalpies of formation and BDE are suggested including for species that to our knowledge there are no experimental (ΔΗf°)m(g) (CHCl2Br, CHBr2Cl, CHBrCl, CHICl, CHIBr) or BDE values (CHCl2Br, CHBr2Cl, CHBrCl, CHICl, CHIBr) available in the literature. The method and calculational procedures presented may profitably be used to obtain accurate (ΔΗf°)m(g) and BDE values for these species.

Gas phase enthalpies of formation of nitrobenzamides using combustion calorimetry and thermal analysis

2014 ◽  
Vol 79 ◽  
pp. 33-40 ◽  
Author(s):  
Arturo Ximello ◽  
Henoc Flores ◽  
Aarón Rojas ◽  
E. Adriana Camarillo ◽  
M. Patricia Amador
Keyword(s):  
Thermal Analysis ◽  
Gas Phase ◽  
Combustion Calorimetry ◽  
Enthalpies Of Formation

The anomalous gas phase acidity of ethyl fluoride. An abinitio investigation of the importance of hydrogen bonding between F− and sp2 and sp C—H bonds

1985 ◽  
Vol 63 (3) ◽  
pp. 708-715 ◽  
Author(s):  
M. Roy ◽  
T. B. McMahon
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Molecular Formula ◽  
Stable Isomer ◽  
Structural Isomers ◽  
Proton Abstraction ◽  
Gas Phase Acidity ◽  
Chemical Techniques ◽  
Gas Phase Ion ◽  
Hydrogen Bonded

Abinitio quantum chemical techniques have been used to investigate the structures and energetics of a number of hydrogen bonded adducts of F− and C—H bonds associated with unsaturated systems as well as their structural isomers. Examination of the possible species of molecular formula C2H4F− reveals that the most stable isomer is a hydrogen bonded adduct of F− and ethylene, while the classical β-fluoroethyl carbanion is found not to be bound with respect to dissociation into F− + C2H4. Similar examination of C2H2F− isomers shows that a hydrogen bonded F−–acetylene adduct is the most stable structure, however, the remaining α and β-fluorovinyl carbanions are found to be bound with respect to F− + C2H2. These results are used to explain the unusual gas phase acidities of ethylfluoride and vinylfluoride. Calculations on C3H4F− isomers show the hydrogen bonded adduct of F− and allene to be more stable than the classical 2-fluoropropenyl anion and on C2H2FO− isomers show the enolate of acetyl fluoride to be more stable than the hydrogen bonded adduct of F− and ketene. These latter results are used to explain the gas phase ion molecule reactivities of C3H4F− (predominantly F− transfer) and C2H2FO− (proton abstraction).

Notizen: Quantum Chemical Investigations on the Structure of the Gas Phase Ion Solvates M+(DMF-CH3+)

1975 ◽  
Vol 30 (12) ◽  
pp. 1792-1793
Author(s):  
B. M. Rode ◽  
R. Ahlrichs
Keyword(s):  
Charge Transfer ◽  
Complex Formation ◽  
Ab Initio ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Basis Sets ◽  
Polarization Effects ◽  
Stabilization Energies ◽  
Gas Phase Ion ◽  
Scf Calculations

Abstract The structure of the dimethylformamide fragment (DMF-CH3+) and its complexes with Li+ and Na+ being observed in low pressure gas phase solvation has been investigated by means of ab initio SCF calculations with two different basis sets. Stabilization energies, charge transfer and polarization effects upon complex formation are discussed.

scholarly journals Weaving a web of reliable thermochemistry around lignin building blocks: phenol, benzaldehyde, and anisole

2021 ◽  
Author(s):  
Sergey P. Verevkin
Keyword(s):  
Phase Transition ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Chemical Method ◽  
Value Added ◽  
Building Blocks ◽  
Enthalpies Of Formation ◽  
Quantum Chemical Method ◽  
Substituted Benzenes ◽  
Energy Balances

Abstract Substituted benzenes such as phenol, benzaldehyde, and anisole are the simplest fragments from the lignin separation feedstocks. We have collected available primary experimental results on vapour pressures, enthalpies of phase transition, and enthalpies of combustion of phenol, benzaldehyde, and anisole. The resulting data on the gas-phase standard molar enthalpies of formation were validated using the quantum chemical method G4. The consistent sets of evaluated thermodynamic data are essential for calculating the energy balances of lignin conversion in the value-added chemicals and materials. Graphic abstract

Sign in / Sign up

Export Citation Format

Share Document