...
  • 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 >Roaming-like Mechanism for Dehydration of Diol Radicals
【24h】

Roaming-like Mechanism for Dehydration of Diol Radicals

机译：二醇自由基脱水的漫游机理

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

Diol radicals (DRs) are important intermediates in biocatalysis, atmospheric chemistry, and biomass combustion. They are particularly generated from photolysis of halogenated diols and addition of hydroxyl radical to a double bond of unsaturated alcohols, such as lignols. The energized DRs further isomerize/decompose to form products, including water. Aqueous-phase dehydration in radiolytic and biomimetic systems typically occurs at low temperatures, with or without catalysis, whereas the gas-phase dehydration is usually considered energetically unfavorable. In the present study, we propose a new low-energy, roaming-like mechanism based on a detailed dispersion-corrected DFT and ab initio level analysis of the gas-phase dehydration of DRs obtained from the combination of OH radicals with allyl alcohol (AA, CH2=CHCH2OH)-the simplest relevant model of the unsaturated alcohols. The roaming pathways involve a nearly dissociated OH-group, which subsequently abstracts an H atom of the remaining fragment to form water and [C3H5O] radical via a transition state (TS) with energy close to the C-O bond fission asymptote. Two types of roaming-like first-order saddle points (SP) are identified for unimolecular dehydration of 1,2- and 1,3-DR radical adducts involving either both hydroxyl groups of diol radicals to generate an oxygen-centered radical, or beta-OH group and a skeletal alpha-hydrogen atom of the 1,2-DR to form a resonantly stabilized hydroxyallyl radical. Two higher energy conventional (tight) transition states, along with the pathways to 1,2-OH-migration, as well as direct H-abstraction, are also identified and analyzed. Most of the traditional density functional theory methods that have been successfully employed in the literature to locate so-far-known roaming SPs were also able to identify the new mechanism, in accord with dispersion-corrected double hybrid B2PLYP-D3(BJ) and mPW2PLYPD methods involving MP2-correlation corrections. However, the MP2 method itself f
机译：二醇自由基（DRS）在生物催化的重要中间体，大气化学和生物质燃烧。它们特别由卤化二醇和另外的羟基自由基与不饱和醇，如lignols的双键的光解产生。通电的存托凭证进一步异构化/分解形成的产品，包括水。在辐射分解和仿生系统水相脱水通常发生在低温下，具有或不具有催化，而气相脱水通常被认为是能量上不利。在本研究中，我们提出了一种新的低能量的基础上，详细色散校正DFT和从头水平从OH自由基的组合获得的DR的气相脱水的用烯丙醇（AA分析漫游状机构，CH 2 = CHCH 2 OH）的不饱和醇的-the简单相关的模型。漫游途径涉及近解离OH基团，其随后抽象的剩余片段，以形成水和[C3H5O]自由基H原子经由过渡态（TS）与能量接近C-O键断裂渐近线。两种类型的漫游状的第一阶鞍点（SP）被识别为的1,2-单分子脱水和1,3- DR自由基加成物涉及两种二醇自由基的两个羟基，以产生氧中心自由基，或β -OH基团和1,2--DR的骨架的α-氢原子以形成共振稳定化的羟基烯丙基基团。两个较高能量常规（紧）过渡态，与该通路沿1,2-OH-迁移，以及直接H-抽象，也被识别和分析。大部分已在文献中已经成功地用于定位，从而远知漫游的SP传统密度泛函理论方法还能够识别新的机制，在符合色散校正双杂交B2PLYP-D3（BJ）和mPW2PLYPD涉及MP2相关的校正方法。然而，MP2方法本身˚F

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