Morgan Kathleen M, Brown Lauren A, Cole Camryn C, Cooper Giavonna K, Nealy Alajah, Seltzer DiJon
Department of Chemistry, Xavier University of Louisiana, 1 Drexel Drive, New Orleans, Louisiana 70125, United States.
J Org Chem. 2025 Jul 25;90(29):10235-10241. doi: 10.1021/acs.joc.5c00777. Epub 2025 Jul 16.
Epoxides are strained heterocycles that are common commodity chemicals and synthetic intermediates. The goal of this study is to understand and compare the reactivity of simple epoxides and their radicals in the gas phase using G4 and W1BD calculations. The epoxides include the parent oxirane and monosubstituted analogs having -CH, -NH, -OH, -F, and -Cl substituents. The C-H bond dissociation energies to form carbon radicals from the various epoxides are reported. Radicals generated on the epoxide ring are nonplanar, and a substituent on the radical carbon has a strong influence on the barrier to invert the radical carbon. Epoxide radicals undergo a competitive ring-opening reaction to form vinoxy radicals, and this process is also influenced by substituents. Calculations on polyfluorinated epoxide radicals were completed, and the barriers to both reactions are elevated in the perfluoro case. These results are largely unchanged when solvent, as incorporated using a polarized continuum model, is included in the calculation. Comparisons to cyclopropyl systems are also made.
环氧化合物是具有张力的杂环化合物，是常见的商品化学品和合成中间体。本研究的目的是使用G4和W1BD计算来理解和比较简单环氧化合物及其自由基在气相中的反应活性。环氧化合物包括母体环氧乙烷和具有-CH、-NH、-OH、-F和-Cl取代基的单取代类似物。报告了由各种环氧化合物形成碳自由基的C-H键解离能。在环氧环上产生的自由基是非平面的，自由基碳上的取代基对自由基碳反转的势垒有很大影响。环氧自由基会发生竞争性的开环反应形成乙烯氧基自由基，这个过程也受取代基影响。完成了对多氟环氧化合物自由基的计算，在全氟情况下，两个反应的势垒都升高了。当使用极化连续介质模型将溶剂纳入计算时，这些结果基本不变。还对环丙基体系进行了比较。
