Combustion Chemistry Centre, School of Chemistry, National University of Ireland, Galway, Ireland 091.
J Phys Chem A. 2012 May 10;116(18):4528-38. doi: 10.1021/jp301870w. Epub 2012 Apr 26.
The enthalpies of formation, entropies, specific heats at constant pressure, enthalpy functions, and all carbon-hydrogen and carbon-methyl bond dissociation energies have been computed using high-level methods for the cyclic ethers (oxolanes) tetrahydrofuran, 2-methyltetrahydrofuran, and 2,5-dimethyltetrahydrofuran. Barrier heights for hydrogen-abstraction reactions by hydrogen atoms and the methyl radical are also computed and shown to correlate with reaction energy change. The results show a pleasing consistency and considerably expands the available data for these important compounds. Abstraction by ȮH is accompanied by formation of both pre- and postreaction weakly bound complexes. The resulting radicals formed after abstraction undergo ring-opening reactions leading to readily recognizable intermediates, while competitive H-elimination reactions result in formation of dihydrofurans. Formation enthalpies of all 2,3- and 2,5-dihydrofurans and associated radicals are also reported. It is probable that the compounds at the center of this study will be relatively clean-burning biofuels, although formation of intermediate aldehydes might be problematic.
使用高精度方法计算了环状醚（四氢呋喃、2-甲基四氢呋喃和 2,5-二甲基四氢呋喃）的生成焓、熵、定压比热容、焓函数以及所有碳-氢键和碳-甲基键离解能。还计算了由氢原子和甲基自由基进行氢提取反应的势垒高度，并显示其与反应能量变化相关。结果表明，这些重要化合物的数据具有令人满意的一致性，并得到了极大的扩展。ȮH 的提取伴随着前反应和后反应的弱束缚复合物的形成。提取后形成的自由基经历开环反应，导致容易识别的中间体，而竞争性的 H 消除反应导致二氢呋喃的形成。还报告了所有 2,3-和 2,5-二氢呋喃及其相关自由基的生成焓。尽管中间醛的形成可能会成为问题，但研究中心的化合物很可能是相对清洁的燃烧生物燃料。
