• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Organic Acid Formation from the Atmospheric Oxidation of Gem Diols: Reaction Mechanism, Energetics, and Rates
【24h】

Organic Acid Formation from the Atmospheric Oxidation of Gem Diols: Reaction Mechanism, Energetics, and Rates

机译：从Gem Diols的大气氧化产生有机酸形成：反应机制，能量和率

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Computational chemistry is used to investigate the gas phase reaction of several gem diols in the presence of OH radical and molecular oxygen (O-3(2)) as would occur in the Earth's troposphere. Four gem diols, represented generically as R-HC(OH)(2), with R being either -H, -CH3, -HC(O), and -CH3C(O) are investigated. We find that after the abstraction of the hydrogen atom from the C-H moiety of the diol by atmospheric OH, molecular oxygen quickly adds onto the resulting radicals leading to the formation of a geminal diol peroxy adduct (R-C(OO)(OH)(2)), which is the key intermediate in the oxidation process. Unimolecular reaction of this R-C(OO)(OH)(2) radical adduct, occurs via a proton-coupled electron transfer (PCET) mechanism and leads to the formation of an organic acid and a HO2 radical. Further, the barrier for the unimolecular reaction step decreases along the R substitution series: -H, -CH3, -HC(O), -CH3C(O); this trend most likely arises from increased internal hydrogen bonding along the series. The reaction where the R group is CH3C(O), associated with methylglyoxal diol, has the lowest barrier with its transition state being similar to 4.3 kcal/mol above the potential energy well of the corresponding CH3C(O)-C(OO)(OH)(2) peroxy adduct. The rate constants for the four diol oxidation reactions were investigated using the MESMER master equation solver kinetics code over the temperature range between 200 and 300 K. The calculations suggest that once formed, gem diol radicals react rapidly with O-2 in the atmosphere to produce organic acids and HO2 with an effective gas phase bimolecular rate constant of similar to 1 x 10(-11) cm(3)/molecule s at 300 K.
机译：计算化学用于研究OH自由基和分子氧的存在（O-3（2））在地球对流层中发生的几个GEM二醇的气相反应。研究了四个宝石二醇，作为R-HC（OH）（2）表示，具有R为-H，-CH 3，-HC（O）和-CH 3C（O）。我们发现，在通过大气oh从二醇的Ch部分抽象氢原子之后，分子氧快速增加到所得的基团上，导致形成孪生二醇过氧加合物（Rc（OO）（OH）（2） ），这是氧化过程中的关键中间体。该R-C（OO）（OH）（2）自由基加合物的单分子反应通过质子偶联的电子转移（PCET）机构发生，并导致形成有机酸和HO2基团。此外，单分子反应步骤的屏障沿R替代系列降低：-H，-CH3，-HC（O），-CH3C（O）;这一趋势最有可能从沿着该系列的内部氢键增加增加。与甲基乙二醇二醇相关的R组是CH 3 C（O）的反应，其过渡状态具有与相应CH 3 C（O）-C（OO）的电位井中高于4.3kcal / mol的屏障（ OH）（2）过氧加合物。使用MESMER总体公式求解器动力学代码在200和300K之间的温度范围内研究了四种二醇氧化反应的速率常数。计算表明，一旦形成，GEM DIOL自由基在大气中迅速反应，在大气中产生有机酸和HO2具有有效的气相双分子率常数，其在300k的300k的1×10（-11）cm（3）/分子S。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号