• 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 >A Computational Study Investigating the Energetics and Kinetics of the HNCO + (CH3)(2)NH Reaction Catalyzed by a Single Water Molecule
【24h】

A Computational Study Investigating the Energetics and Kinetics of the HNCO + (CH3)(2)NH Reaction Catalyzed by a Single Water Molecule

机译：调查单水分分子催化的HNCO +（2）NH反应的能量和动力学的计算研究

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

High-level ab initio calculations are used to explore the energetics and kinetics for the formation of 1,1-dimethyl urea via the reaction-of isocyanic acid (HNCO) with dimethyl amine (DMA) catalyzed by a single water molecule. Compared to the uncatalyzed HNCO + DMA reaction, the presence of a water molecule lowers the reaction barrier, defined here as the energy difference between the separated HNCO + DMA + H2O reactants and the transition state (TS), by similar to 26 kcal/mol. In addition to the HNCO + DMA + H2O reaction, the energetics of the analogous reactions involving, respectively, ammonia and methyl amine were also investigated. Comparing the barriers for these three amine addition reactions, which can be represented as HNCO + R-NH-R' + H2O with Rand R' being either -CH3 or -H, we find that the reaction barrier decreases with the degree of methylation on the amine nitrogen atom. The effective rate constants for the bimolecular reaction pathways HNCO center dot center dot H2O + DMA and HNCO center dot center dot DMA + H2O were calculated using canonical variational TS theory coupled with both small curvature and zero-curvature tunneling corrections over the 200-300 K temperature range. For comparison, we also calculated the rate constant for the HNCO + OH reaction. Our results suggest that the HNCO + H2O + DMA reaction can make a non-negligible contribution to the gas-phase removal of atmospheric HNCO under conditions where the HNCO and water concentrations are high and the temperature is low.
机译：高级别从头计算用于探索能量学和动力学用于经由异氰酸反应的氰酸（HNCO）与由单一水分子催化二甲基胺（DMA）形成1,1-二甲基尿素。相较于非催化HNCO + DMA反应中，水分子的存在降低了反应阻挡，这里定义为之间的能量差而分离HNCO + DMA + H 2 O反应物和过渡态（TS），通过类似于26千卡/摩尔。除了HNCO + DMA + H 2 O反应，涉及分别的类似反应的能量学，氨和甲胺进行了研究。障碍这三种胺的加成反应，其可以被表示为HNCO + R-NH-R“+ H 2 O与R和R”是任-CH 3或-H比较，我们发现反应阻挡与甲基化的程度降低胺氮原子。为双分子反应途径HNCO中心点中心的点H 2 O + DMA和HNCO中心点中心的点DMA + H2O的有效速率常数计算使用正则变分TS理论加上两个小的曲率和零曲率隧道效应校正在200-300ķ温度范围。为了比较，我们还计算了HNCO + OH反应的速率常数。我们的研究结果表明，HNCO + H 2 O + DMA反应可以对其中HNCO和水浓度高，温度低的条件下的气相除去大气HNCO的不可忽略的贡献。

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