Dynamics for Reactions of Ion Pairs in Aqueous Solution: Reactivity of Tosylate Anion Ion Paired with the Highly Destabilized 1-(4-Methylphenyl)-2,2,2-Trifluoroethyl Carbocation.
Dynamics for Reactions of Ion Pairs in Aqueous Solution: Reactivity of Tosylate Anion Ion Paired with the Highly Destabilized 1-(4-Methylphenyl)-2,2,2-Trifluoroethyl Carbocation.
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水溶液中离子对反应动力学：甲苯磺酸根阴离子与高度不稳定的 1-(4-甲基苯基)-2,2,2-三氟乙基碳阳离子配对的反应性。
DOI：
10.1002/poc.1642
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发表时间：
2010
影响因子：
1.8
通讯作者：
Richard,JohnP
中科院分区：
文献类型：
--
作者：
Teshima,Minami;Tsuji,Yutaka;Richard,JohnP
在 50/50 (v/v) 三氟乙醇/水中，4-MeC6H4CH(CF3)OS(18O2)Tos 下碳桥和非桥氧 18 的溶剂分解和加扰速率常数之和 (ksolv+kiso) = 5.4 × 10−6s−1 大 50%感谢solv= 3.6 × 10−6用于磺酸酯的简单溶剂解反应。这表明溶剂分解的离子对中间体经历显着的内部返回以形成反应物。这些数据给出了碳正离子对到底物内部返回的值 k-1= 1.7 × 1010s−1。该速率常数大于 k-1= 7 × 109s−1 的值，该值报告为在相同溶剂中 1-(4-甲基苯基)乙基碳阳离子和五氟苯甲酸根阴离子之间的离子对内部返回到中性酯 (4-MeC6H4CH(CH3)O2CC6F5)。比较和对比了 1-(4-甲基苯基)乙基碳阳离子和高度不稳定的 1-(4-甲基苯基)2,2,2-三氟乙基碳阳离子的离子对分配。版权所有 © 2010 约翰威利父子有限公司
The sum of the rate constants for solvolysis and scrambling of carbon bridging and nonbridging oxygen‐18 at 4‐MeC6H4CH(CF3)OS(18O2)Tos in 50/50 (v/v) trifluoroethanol/water, (ksolv+kiso) = 5.4 × 10−6s−1, is 50% larger thanksolv= 3.6 × 10−6for the simple solvolysis reaction of the sulfonate ester. This shows that the ion‐pair intermediate of solvolysis undergoes significant internal return to form reactant. These data give a value ofk‐1= 1.7 × 1010s−1for internal return of the carbocation–anion pair to the substrate. This rate constant is larger than the value ofk‐1= 7 × 109s−1reported for internal return of an ion pair between the 1‐(4‐methylphenyl)ethyl carbocation and pentafluorobenzoate anion to the neutral ester (4‐MeC6H4CH(CH3)O2CC6F5) in the same solvent. The partitioning of ion pairs to the 1‐(4‐methylphenyl)ethyl carbocation and to the highly destabilized 1‐(4‐methylphenyl)2,2,2‐trifluoroethyl carbocation is compared and contrasted. Copyright © 2010 John Wiley & Sons, Ltd.