Tunneling in the 1,5-Hydrogen Shift Reactions of 1,3-Cyclopentadiene and 5-Methyl-1,3-Cyclopentadiene

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• 作者：G. Robert Shelton ; David A. Hrovat ; Weston Thatcher Borden
• 刊名：Journal of the American Chemical Society
• 出版年：2007
• 出版时间：January 10, 2007
• 年：2007
• 卷：129
• 期：1
• 页码：164 - 168
• 全文大小：95K
• 年卷期：v.129,no.1(January 10, 2007)
• ISSN：1520-5126

文摘

MPW1K/6-31+G(d,p) calculations which include the effects of small curvature tunneling findthat, around room temperature, thermally activated tunneling dominates the 1,5-hydrogen shift reactionsof 1,3-cyclopentadiene (2a) and 5-methyl-1,3-cyclopentadiene (2c). The calculated temperature dependenceof the H/D kinetic isotope effect (KIE) for the latter rearrangement agrees well with experimentalmeasurements that were published nearly 40 years ago. It is argued that the experimental KIEs provideprima facie evidence for tunneling in this reaction. The calculations also predict that it should be possible,at least in principle, to confirm this conclusion by observing curvature in the Arrhenius plot for therearrangement of 2c.