5.2 Stability of benzene From high temperature distillation of coal tar Heating petroleum at high temperature and pressure over a catalyst KMnO4 HO HX
5.2 Stability of Benzene • From high temperature distillation of coal tar • Heating petroleum at high temperature and pressure over a catalyst KMnO4 HX H3O +
Heats of hydrogenation as Indicators of Stability E (kJ/ mol 假想的环己三烯 实际存在的苯 +3H2 2H2+ +3H 36 232 H2+ 209 120
H2 + 209 232 120 336 2H2 3H2 ( kJ / mol ) + + + 3H2 假想的环己三烯 实际存在的苯 E Heats of Hydrogenation as Indicators of Stability
5.3 Structure of benzene The resonance proposal ……④
5.3 Structure of Benzene: The Resonance Proposal + -
157 ** Aromaticity and the Huckel 4n+2 rule 芳香性和 Huckel4n+2规如 a molecule is aromatic only if it has a planar, monocyclic system of conjugation with a total of 4n+2 I electrons where n is an integer 在一个平面单环热軛体系中,含有4n+2电 子的体系具有与惰性气体相类似的闭壳层结构,从而 显示出芳香性
**Aromaticity and the Huckel 4n+2 rule 芳香性和 Huckel 4n+2规则 p.157 “A molecule is aromatic only if it has a planar, monocyclic system of conjugation with a total of 4n+2 p electrons, where n is an integer. 在一个平面 单环 共軛 体系中, 含有4n+2 p电 子的体系具有与惰性气体相类似的闭壳层结构, 从而 显示出芳香性
aromaticity and the 4n+2 Rule For n=1 4n+2=6 benzene is stable and the electrons are delocalized Benzene Three double bonds six electrons Thomson.Brooks Cole
Aromaticity and the 4n + 2 Rule For n=1: 4n+2 = 6; benzene is stable and the electrons are delocalized