A group equivalents scheme for free energies of formation of organic compounds in aqueous solution

J. Peter Guthrie

doi:10.1139/v92-139

A group equivalents scheme for free energies of formation of organic compounds in aqueous solution

Canadian Journal of Chemistry ◽

10.1139/v92-139 ◽

1992 ◽

Vol 70 (4) ◽

pp. 1042-1054 ◽

Cited By ~ 19

Author(s):

J. Peter Guthrie

Keyword(s):

Aqueous Solution ◽

Organic Compounds ◽

Group Contributions ◽

Free Energies

Group contributions have been determined allowing the calculation of free energies of formation in aqueous solution for organic compounds containing carbon, hydrogen, and oxygen. The system works well for monofunctional compounds. The available literature data for 198 compounds can be accommodated using 79 parameters with an rms deviation of 0.74 kcal/mol.

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Additivity schemes permitting the estimation of partial molar heat capacities of organic compounds in aqueous solution

Canadian Journal of Chemistry ◽

10.1139/v77-519 ◽

1977 ◽

Vol 55 (21) ◽

pp. 3700-3706 ◽

Cited By ~ 34

Author(s):

J. Peter Guthrie

Keyword(s):

Aqueous Solution ◽

Organic Compounds ◽

Weighted Average ◽

Heat Capacities ◽

Group Contributions ◽

Partial Molar Heat Capacities ◽

Neutral Organic Compounds

The available [Formula: see text] values for neutral organic compounds in aqueous solution can be fitted with useful precision by additivity schemes based on atomic, bond, or group contributions. For the set of 132 compounds these schemes require 11, 14, or 49 parameters and give weighted average deviations of 14, 9, or 6 J K−1 mol−1. For acyclic molecules the atomic contributions scheme permits chemically useful estimates of [Formula: see text] to be made for compounds of C, H, O, and N.

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2-Deoxyribose Radicals in the Gas Phase and Aqueous Solution. Transient Intermediates of Hydrogen Atom Abstraction from 2-Deoxyribofuranose

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20051769 ◽

2005 ◽

Vol 70 (11) ◽

pp. 1769-1786 ◽

Cited By ~ 4

Author(s):

Luc A. Vannier ◽

Chunxiang Yao ◽

František Tureček

Keyword(s):

Aqueous Solution ◽

Hydrogen Atom ◽

Gas Phase ◽

Computational Study ◽

Hydrogen Atom Abstraction ◽

Oh Radical ◽

Free Energies ◽

Intramolecular Hydrogen ◽

Solvation Free Energies ◽

Transient Intermediates

A computational study at correlated levels of theory is reported to address the structures and energetics of transient radicals produced by hydrogen atom abstraction from C-1, C-2, C-3, C-4, C-5, O-1, O-3, and O-5 positions in 2-deoxyribofuranose in the gas phase and in aqueous solution. In general, the carbon-centered radicals are found to be thermodynamically and kinetically more stable than the oxygen-centered ones. The most stable gas-phase radical, 2-deoxyribofuranos-5-yl (5), is produced by H-atom abstraction from C-5 and stabilized by an intramolecular hydrogen bond between the O-5 hydroxy group and O-1. The order of radical stabilities is altered in aqueous solution due to different solvation free energies. These prefer conformers that lack intramolecular hydrogen bonds and expose O-H bonds to the solvent. Carbon-centered deoxyribose radicals can undergo competitive dissociations by loss of H atoms, OH radical, or by ring cleavages that all require threshold dissociation or transition state energies >100 kJ mol-1. This points to largely non-specific dissociations of 2-deoxyribose radicals when produced by exothermic hydrogen atom abstraction from the saccharide molecule. Oxygen-centered 2-deoxyribose radicals show only marginal thermodynamic and kinetic stability and are expected to readily fragment upon formation.

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