离子液体中卤素交换氟化合成七氟醚

在离子液体作为反应介质的条件下,以六氟异丙基氯甲基醚的氟代反应合成了七氟醚。 探讨了氟代反应机理,考察了[bpy]BF4、[bmim]BF4、[bepy]BF4、[bmim]PF6对反应产率的影响,研究了氟化剂、水和温度对反应产率的影响。 结果表明,以[bepy]BF4为反应介质,高比表面积的KF和微量的水有利于固态KF的部分离解进入有机相形成高活性的F-从而减少副产物,收率达到94.6%。 离子液体可重复使用3次以上,其活性没有明显下降。     

Ab Initio Calculation of structures and properties of halogenated general anesthetics: halothane and sevoflurane

To correctly analyze the effects of general anesthetics on their potential targets by large‐scale molecular simulation, the structural parameters and partial atomic charges of the anesthetics are of determinant importance. Geometric optimizations using the Hartree–Fock and the B3LYP density functional theory methods with the large 6‐311+G(2d,p) basis set were performed to determine the structures and charge distributions of two halogenated anesthetics, 2‐bromo‐2‐chloro‐1,1,1‐trifluoroethane (halothane) and fluoromethyl‐2,2,2,‐trifluoro‐1‐(trifluoromethyl) ethyl ether (sevoflurane). The calculated bond lengths and angles are within 3% of the corresponding experimental values reported for the similar molecular groups. Charges are assigned using the Mulliken population analysis and the electrostatic potential (ESP) based on the Merz–Kollman–Singh scheme. The atoms‐in‐molecules (AIM) theory is also used to assign the charges in halothane. The dipole moments calculated with the Mulliken population analysis and ESP for the structures optimized by B3LYP/6‐311+(2d,p) were respectively 1.355 and 1.430 D for halothane and 2.255 and 2.315 D for sevoflurane. These are in excellent agreement with the experimental values of 1.41 and 2.33 D for halothane and sevoflurane, respectively. The calculated structures and partial charge distributions can be readily parameterized for molecular mechanics and molecular dynamics simulations involving these halogenated agents. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 436–444, 2001     

两种七氟醚自由基[(CF3)2C(·)OCH2F,(CF3)2CHOC(·)HF]与氧气反应及OH·再生机理的理论研究

温室气体七氟醚氧化降解可以产生两种反应活性截然不同的自由基，即（CF₃）₂C（·）OCH₂F与（CF₃）₂CHOC（·）HF.采用M06-2X/6-311++G（d，p）与CBS-Q理论方法研究了两种七氟醚自由基与氧气（O₂）反应的机理.与普通的烷基自由基+O₂的无垒复合反应不同，多氟取代的七氟醚自由基与O₂反应需经过1.3~1.8 kcal·mol^-1的势垒才能生成过氧自由基中间体RO₂·.虽然O₂更易于加成到富氟的自由基位点，但与贫氟自由基位点结合生成RO₂·放热更多，且随后的六中心氢迁移生成QOOH中间体需要克服更高的势垒.QOOH分解包括三种主要的OH·再生途径，即：分步解离、三体同步解离、四中心分子内S_N2反应.对于（CF₃）₂C（OC（·）HF）OOH，三条途径互为竞争；对于（CF₃）₂C（·）OC（HF）（OOH），分子内S_N2反应为OH·再生的主要途径，分步或三体同步解离则为次要机理.研究为阐明多氟取代基对大气中OH·循环的影响规律提供了理论依据.