الفهرس | Only 14 pages are availabe for public view |
Abstract The present work aims to study the thermochemistry and kinetics of 2-butanol decomposition either through bimolecular oxidation using methyl, hydroxyl, hydroperoxyl and hydrogen radicals. The obtained results were compared with those obtained for n-butanol because of molecular weight similarity of the two compounds and to show the effect of presence etheric oxygen upon the abstraction mechanism. 2-butanol has many advantages includes high internal energy, low vapor pressure, low toxicity and hydropholic than ethanol. The potential energy diagrams for all of the investigated channels were constructed at BMK, CBS-APNO, G3, G3B3, G4MP2, and CBS-QB3 levels of theory. Finally, rate constant calculations for all channels at different temperatures were computed using the conventional transition state theory (TST) with Wigner correction. All channels of oxidation of 2-butanol by H radical are exothermic at CBS-QB3. Based on the calculated energy barriers for oxidation channels, the order for H-abstraction reactions is the order of site is given Cα< Cβ < Cϒ < Cβm < O at CBS-QB3. H-abstraction from Cα has the lowest energy barrier because it forms the most stable radical due to the presence of higher degree of hyperconjugation with the five C-H bonds. Oxidation of 2-butanol by OH show H-abstraction reactions is the order of site is given Cα< Cβ < Cϒ < Cβm < O at CBS-QB3. H-abstraction from Cα has the lowest energy barrier because it forms the most stable radical that is stabilized due to the presence of higher degree of hyperconjugation, five C-H bonds can interact with the radical center. Moreover, some transition states can be stabilized by the presence of intramolecular hydrogen bond between the attacking hydroperoxyl radical and the alcoholic OH. |