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High Pressure Studies of the Dynamic Solvent Effect in Chemical Reactions in Solution

溶液中化学反应动态溶剂效应的高压研究

基本信息

批准号：
09640602
负责人：
HARA Kimihiko
金额：
$ 1.98万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

The purpose of this project is to understand the "dynamic solventeffect" in the isomerizations with large amplitude rotational motion. Following two main subjects are included ; 1) dynamic solvent effect in theisomerization acompanying with intramolecular charge-transfer and 2)dynamic solvent effect in the non-polar isomerization in non-polar solvent. Here, the high pressure technique has been employed as a powerful methodfor chnaging solvent viscosity continuously and widely without modifyingthe solvent potential energy.1) Dynamic solvent effect of the isomerization with charge-transfer : The rate-constant of "twisted intramolecular charge-transfer (TICT)" stateformation (kTICT) for 4-(N,N dimethylamino)trinitrophosphine (DMATP) hasbeen determined as a function pressure. kTICT has been studied as afunction of solvent shear viscosity. Solvation has been discussed byusing longitudinal relaxation of solvent (tL) as a measure of solvationtime scale. We found that the reaction path is understood as the shiftfrom solvation controlled to intramolecular vibration controlled scheme.2) Dynamic solvent effect on non-polar isomerization in non-polarsolvent : The reaction system studied is the Si state isomerization of2-vinylanthracene (I) and 2,2 propenylanthracene (II). The rate constantsof both isomerization reactions have been determined in the series ofalkane solvents frome supercritical ethane to compressed liquid phaseoctane. i) In the high viscosity condition at high pressure where thereaction is controlled by spatial diffusion, the shows non-Kramers behavior. ii) In low viscosity at low pressure where the reaction iscontrolled by energy diffusion, it increases with a same activation energyas in the liqui phase condition. iii) "Kramers turnover" has been observed.iv) The turnover plateau for II locates in the lower viscosity region ascompared with I.

本项目的目的是了解具有大振幅旋转运动的异构化反应中的“动态溶剂效应”。主要包括以下两个方面的内容：1)分子内电荷转移伴随的异构化反应中的动态溶剂效应；2)非极性溶剂中非极性异构化反应中的动态溶剂效应。在这里，高压技术是一种在不改变溶剂势能的情况下连续和广泛地改变溶剂粘度的有效方法：1)电荷转移异构化的动态溶剂效应：确定了4-(N，N二甲氨基)三硝基膦(DMATP)的“扭曲分子内电荷转移(TICT)”状态形成(KTICT)的速率常数为函数压力。研究了KTICT作为溶剂剪切粘度的函数。用溶剂的纵向松弛(TL)作为溶剂时间尺度的量度，对溶剂化进行了讨论。2)非极性溶剂对非极性异构化反应的动态溶剂效应：所研究的反应体系为2-乙烯基茂(I)和2，2-丙烯基茂(II)的硅态异构化反应。测定了两种异构化反应在从超临界乙烷到压缩液相辛烷的系列烷烃溶剂中的速率常数。I)在高压高粘度条件下，反应受空间扩散控制，表现为非Kramers行为。Ii)在低粘度、低压力、反应受能量扩散控制的情况下，它以与液相条件相同的活化能增加。Iii)观察到了Kramers周转现象。