降冰片烷中碳氢键的解离焓：一项实验与计算研究

C-H bond dissociation enthalpies in norbornane. An experimental and computational study.

作者信息

Nunes Paulo M, Estacio Sílvia G, Lopes Gustavo T, Costa Cabral Benedito J, Borges dos Santos Rui M, Martinho Simões José A

机构信息

Centro de Química e Bioquímica and Departamento de Química e Bioquímica Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal.

出版信息

Org Lett. 2008 Apr 17;10(8):1613-6. doi: 10.1021/ol800333q. Epub 2008 Mar 19.

DOI:10.1021/ol800333q

PMID:18348570

Abstract

Gas-phase C-H bond dissociation enthalpies (BDEs) in norbornane were determined by quantum chemistry calculations and the C2-H BDE was experimentally obtained for the first time by time-resolved photoacoustic calorimetry. CBS-Q and CBS-QB3 methods were used to derive the values DH degrees (C1-H) = 449 kJ mol-1, DH degrees (C7-H) = 439 kJ mol-1, and DH degrees (C2-H) = 413 kJ mol-1. The experimental result DH degrees (C2-H) = 414.6 +/- 5.4 kJ mol-1 is in excellent agreement with the theoretical value. The trend DH degrees (C1-H) > DH degrees (C7-H) > DH degrees (C2-H) is discussed.

摘要

通过量子化学计算确定了降冰片烷中气相C-H键的离解焓（BDEs），并首次通过时间分辨光声量热法实验获得了C2-H的BDE。采用CBS-Q和CBS-QB3方法得出以下数值：ΔH°(C1-H) = 449 kJ mol-1，ΔH°(C7-H) = 439 kJ mol-1，以及ΔH°(C2-H) = 413 kJ mol-1。实验结果ΔH°(C2-H) = 414.6 ± 5.4 kJ mol-1与理论值高度吻合。文中讨论了ΔH°(C1-H) > ΔH°(C7-H) > ΔH°(C2-H)这一趋势。