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Molecular dynamics study of the tautomeric equilibrium in the 4-nitro- and 2,4,6-trichloro derivatives of 2-( N , N -dialkyloaminomethyl)phenol.

Authors
Fedorowicz-A; Koll-A; Mavri-J
Source
Theor Chem Acc 2003 May; 109(4):220-228
NIOSHTIC No.
20033267
Abstract
Molecular dynamics thermodynamic integration (MDTI) method and quantum chemical calculations at the density functional theory B3LYP 6-31+(d,p) level, which included the Tomasi model of the solvent reaction field, were applied to study the tautomeric equilibrium of Mannich base in methanol solution. The values obtained for the free-energy difference are in good agreement with experimental data. However, the results from quantum mechanical calculations were not as good as the results of MDTI simulations owing to inappropriate treatment of intermolecular hydrogen bonds between the solute molecule and the first shell of solvent molecules in the Tomasi model of the solvent reaction field. The radial distribution functions between solute atoms and solvent atoms confirmed the formation of hydrogen bonds between the solute molecule and surrounding methanol molecules and indicated that the zwitterionic form is associated more with an organized solvent structure at the level of the first solvation shell than is the molecular form.
Keywords
Molecular-biology; Thermodynamic-reactions; Thermodynamics; Solvents; Chemical-properties; Chemical-binding
Contact
A. Fedorowicz, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505
CODEN
TCACFW
Publication Date
20030501
Document Type
Journal Article
Fiscal Year
2003
NTIS Accession No.
NTIS Price
Issue of Publication
4
ISSN
1432-881X
NIOSH Division
HELD
Source Name
Theoretical Chemistry Accounts
State
WA; NC; MI; WV
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