...
  • 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, B. Condensed matter, materials, surfaces, interfaces & biophysical >Experimental and Theoretical Studies on Structure-Reactivity Relationships of Titanium-Modified Silicas in the Hydrogen Peroxide-Promoted Oxidation of Cyclohexene
【24h】

Experimental and Theoretical Studies on Structure-Reactivity Relationships of Titanium-Modified Silicas in the Hydrogen Peroxide-Promoted Oxidation of Cyclohexene

机译：过氧化氢促进环己烯氧化钛修饰二氧化硅结构反应性关系的实验和理论研究

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

Theoretical calculations demonstrate that the presence of ligands with different basicity modifies the Lewis acidity (expressed both as the LUMO energy and the enthalpy of coordination of a NH_3 molecule) of the active centers in silica-supported titanium catalysts. Several catalysts containing different organic ligands bonded to the titanium centers have been prepared, characterized, and tested in the benchmark reaction of cyclohexene with hydrogen peroxide. Both the activity and the selectivities of the catalysts depend on the relative basicity of the ligands and their variation is proportional to the calculated Lewis acidity, expressed as the LUMO energy. With more basic ligands, hydrolysis of the epoxide to diol occurs to a lesser extent at the expense of the catalytic activity and the epoxidation/allylic oxidation selectivity, showing the coincidence of the active sites for epoxidation and hydrolysis reactions.
机译：理论计算表明，具有不同碱性的配体的存在会改变二氧化硅负载的钛催化剂中活性中心的路易斯酸度（表示为LUMO能量和NH_3分子的配位焓）。在环己烯与过氧化氢的基准反应中，已经制备，表征和测试了几种含有键合到钛中心的不同有机配体的催化剂。催化剂的活性和选择性都取决于配体的相对碱性，它们的变化与计算出的路易斯酸度成正比，表示为LUMO能量。在具有更多碱性配体的情况下，环氧化物水解成二醇的程度较小，但以催化活性和环氧化/烯丙基氧化选择性为代价，这表明环氧化和水解反应的活性位重合。

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