Conformational Isomerization of 1,2-Difluoroethane in Solid Argon: Cage-Modified Reaction Barriers
Conformational Isomerization of 1,2-Difluoroethane in Solid Argon: Cage-Modified Reaction Barriers
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1,2-二氟乙烷在固体氩中的构象异构化：笼式改进的反应势垒
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
C. Wight
中科院分区：
文献类型：
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作者：
Alexander V. Benderskii and;C. Wight
在30 - 36 K温度范围内，用红外光谱研究了反式-1，2-二氟乙烷在Ar基质中热诱导旋转异构化为更稳定的gauche构象。光化学生成的1，2-二氟乙烷在基质中由两种不同的机制形成的产品在单和双取代的氩晶格网站。只有更稳定的双取代的网站是由普通气相沉积技术填充。在33 K时，单中心异构化反应的一级速率常数为1.0 × 10- 5s-1，而双中心异构化反应的一级速率常数为5 × 10- 3s-1。温度依赖性异构化速率的测定表明，单中心和双中心异构化反应的活化能分别为15.0 ± 1.5和9.7 ± 0.8kJ/mol。后者的值接近最近估计的气相反应势垒（8.86千焦/摩尔）。这项研究提供了一个重要的例子，反应屏障是如何显着修改的固相反应。
Thermally induced rotational isomerization of trans-1,2-difluoroethane into the more stable gauche conformer in Ar matrices was studied over the temperature range 30−36 K by infrared spectroscopy. Photochemical generation of 1,2-difluoroethane in the matrix by two different mechanisms forms the product in singly and doubly substitutional argon lattice sites. Only the more stable doubly substitutional site is populated by the ordinary vapor deposition technique. At 33 K, the first-order rate constant for isomerization in the single site is 1.0 × 10-5 s-1 whereas the corresponding value for the double site is 5 × 10-3 s-1. Measurements of the temperature-dependent isomerization rates show that the activation energies for molecules in single and double sites are 15.0 ± 1.5 and 9.7 ± 0.8 kJ/mol, respectively. The latter value is close to a recent estimate of the gas phase reaction barrier (8.86 kJ/mol). This study provides an important example of how a reaction barrier is significantly modified by a solid-sta...