Thermochemistry of 2- and 3-thiopheneacetic acids: calorimetric and computational study.
The enthalpies of formation in the condensed and gas states, Delta f H m degrees (cd) and Delta f H m degrees (g), of 2- and 3-thiopheneacetic acids were derived from their respective enthalpies of combustion in oxygen, measured by a rotating bomb calorimeter, and the variation of vapor pressure with temperature determined by the Knudsen effusion technique. Theoretical calculations at the G3 level were performed, and a study on molecular and electronic structure of the compounds has been carried out. Calculated Delta f H m degrees (g) values using atomization and isodesmic reactions are compared with the experimental data. Experimental and theoretical results show that the 3-thiopheneacetic acid is thermodynamically more stable than the 2-isomer.
Temprado
Manuel
M
Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain.
Roux
María Victoria
MV
Jiménez
Pilar
P
Foces-Foces
Concepción
C
Notario
Rafael
R
D000085:Acetates / Q000737:chemistry*; D002151:Calorimetry; D003198:Computer Simulation; D004583:Electrons; D008956:Models, Chemical; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry; D011312:Pressure; D011789:Quantum Theory; D013696:Temperature; D013816:Thermodynamics; D013876:Thiophenes / Q000737:chemistry*
C517218:3-thiophene acetic acid; D000085:Acetates; D013876:Thiophenes; C017754:2-thienylacetic acid; D010100:Oxygen