Thermochemistry of biphenylcarboxylic and dicarboxylic acids. A combined experimental and theoretical study.
The standard molar enthalpies of combustion and sublimation of 2- and 4-biphenylcarboxylic acid, 2,2'- and 4,4'-biphenyldicarboxylic acid were measured and the gas-phase enthalpies of formation, at T= 298.15 K, were determined. Ab initio calculations were performed and a theoretical study on molecular structure of all the biphenyl acid isomers has been carried out. Calculated enthalpies of formation using appropriate isodesmic reactions are compared with experimental values, and a good agreement is observed. Estimates of enthalpies of formation for the isomers, which were not studied experimentally, are presented. All the acids containing at least one ortho COOH are comparatively less stable than their isomers having just meta or para COOH group(s).
Matos
M Agostinha R
MA
Centro de Investigacao em Quimica, Departamento de Quimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto, Portugal. marmatos@fc.up.pt
Miranda
Margarida S
MS
Martins
Diana V S S
DV
Pinto
Natália A B
NA
Morais
Victor M F
VM
Liebman
Joel F
JF