標題: Computational study on the kinetics and mechanisms for the unimolecular decomposition of formic and oxalic Acids
作者: Chang, Jee-Gong
Chen, Hsin-Tsung
Xu, Shucheng
Lin, M. C.
應用化學系分子科學碩博班
Institute of Molecular science
公開日期: 26-七月-2007
摘要: The kinetics and mechanisms for the unimolecular decomposition reactions of formic acid and oxalic acid have been studied computationally by the high-level G2M(CC1) method and microcanonical RRKM theory. There are two reaction pathways in the decomposition of formic acid: The dehydration process starting from the Z conformer is found to be the dominant, whereas the decarboxylation reaction starting from the E conformer is less competitive. The predicted rate constants for the dehydration and decarboxylation reactions are in good agreement with the experimental data. The calculated CO/CO2 ratio, 13.6-13.9 between 1300 and 2000 K, is in close agreement with the ratio of 10 measured experimentally by Hsu et al. (In The 19th International Symposium on Combustion; The Combustion Institute: Pittsburgh, PA, 1983; p 89). For oxalic acid, its isomer with two intramolecular hydrogen bonds is the most stable structure, similar to earlier reports. Two primary decomposition channels of oxalic acid producing CO2 + HOCOH with barriers of 33-36 kcal/mol and CO2 + CO + H2O with a barrier of 39 kcal/mol were found. At high temperatures, the latter process becomes more competitive. The rate constant predicted for the formation of CO2 and HOCOH (the precursor of HCOOH) agrees well with available experimental data. The mechanism for the isomerization of HOCOH to HCOOH is also discussed.
URI: http://dx.doi.org/10.1021/jp069036p
http://hdl.handle.net/11536/10546
ISSN: 1089-5639
DOI: 10.1021/jp069036p
期刊: JOURNAL OF PHYSICAL CHEMISTRY A
Volume: 111
Issue: 29
起始頁: 6789
結束頁: 6797
顯示於類別:期刊論文


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