Department of Chemical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States.
J Phys Chem A. 2019 Nov 14;123(45):9644-9657. doi: 10.1021/acs.jpca.9b05806. Epub 2019 Oct 30.
Despite the promising role of cyclopentanone as a bioderived fuel, thermodynamic and kinetic data are lacking for low temperature oxidation regimes. In this study, calculations at the CBS-QB3 level explore the subsequent reactivity that results from O-addition to 2- and 3-oxo cyclopentyl radicals, including expected reaction classes such as intra-H migration, HO-elimination, cyclic ether formation, and β-scission along with their thermodynamic parameters. Some of the rates are similar to the analogous reactions of cyclopentane, but some other reactions of cyclopentanone are very different. The carbonyl group hinders H-migration from the α' position but promotes HO-elimination. Enol peroxy formation from some hydroperoxy alkyl radicals of cyclopentanone is unexpectedly important, and so is HO-elimination by β-scission. Our calculations also indicated that at engine relevant conditions the α-RO prefers to go back to the reactants 2-oxo cyclopentyl radical and O. Therefore, the reactions resulting from HO-addition to 2-oxo cyclopentyl are also provided. The lowest barrier channel identified on the singlet surface corresponds to an unexpected intra OH-migration path concerted with ring opening. This valuable information will advance the construction of improved kinetic models for the oxidation of cylopentanone.
尽管环戊酮作为一种生物衍生燃料具有很大的发展潜力，但在低温氧化条件下，其热力学和动力学数据仍然缺乏。在这项研究中，我们使用 CBS-QB3 理论水平计算了氧加成到 2-和 3-氧环戊基自由基后的后续反应性，包括预期的反应类型，如内 H 迁移、HO 消除、环状醚形成和β-断裂，以及它们的热力学参数。其中一些速率与环戊烷的类似反应相似，但环戊酮的其他一些反应则非常不同。羰基基团阻碍了α'位置的 H 迁移，但促进了 HO 消除。一些环戊酮的氢过氧烷基自由基形成烯醇过氧是出乎意料的重要，β-断裂的 HO 消除也是如此。我们的计算还表明，在发动机相关条件下，α-RO 更倾向于回到反应物 2-氧环戊基自由基和 O。因此，我们也提供了 HO 加成到 2-氧环戊基的反应。在单重态表面上，确定的最低能垒通道对应于一个意想不到的内 OH-迁移路径，与开环协同进行。这些有价值的信息将推动改进环戊酮氧化动力学模型的构建。
