Kekule's model of benzene Disadvantage of Kekule's benzene Br Br -HBr Friedrich Kekule Kekule's original model of benzene (1865) Structure of benzene Structure of benzene ,C-C键长均为139pm ·键角均为120°，碳与氢共平面 37人 a ·六个碳均为sp杂化，相邻碳形成σ键 ·未杂化轨道形成大π键 π电子离域，电子云密度平均化 Unusual stability Nomenclature 篷 巴 CH T 苯乙烯 甲苯 (phenylethene) (toluene) CH,CH-CH2 3-苯基丙烯 (3-phenylpropene) 22 Prepared by Yang R. L. Kekulé’s original model of benzene (1865) Friedrich Kekulé Kekulé’s model of benzene Prepared by Yang R. L. Br Br Br Br Br Br2 / FeBr3 -HBr + + Br Br Br Br ≡ Disadvantage of Kekulé’s benzene Prepared by Yang R. L. Structure of benzene • 六个碳均为sp2杂化，相邻碳形成s键 • 未杂化轨道形成大p键 • p电子离域，电子云密度平均化 Prepared by Yang R. L. Structure of benzene • C-C键长均为139pm • 键角均为120°，碳与氢共平面 Prepared by Yang R. L. Unusual stability Prepared by Yang R. L. 甲苯 (toluene) CH3 CH2CH=CH2 3-苯基丙烯 (3-phenylpropene) Nomenclature C H CH2 苯乙烯 (phenylethene)