Aromatic hydrocarbon* 单环（苯及同系物） 苯型芳香烃 稠环 Chapter 4 芳香烃 Aromatic hydrocarbon 非苯型芳香烃 Discovery of benzene*() Physical properties of benzene ·l825由Michael Faraday从煤焦油中分得， Colorless liquid 确定C:H为1：1 ·b.p.80.08℃mp.5.48C ·1834由Eilhard Mitscherlich合成，确定分子 ·Density0.880g/cm3 式为CH。 Insoluble in water and soluble in oils and fats ·类似具有高C:H的化合物也具有芳香气味， 因此称为芳香化合物 Properties of benzene Proposed structures of benzene ·分子式CH6 ·六个H完全相同 ·一个单取代物，二、三、四取代物各有三 Kekul'e Dewar benzene Ladenburg prismane 1865 1866-1867 1869 种，五、六取代物各有一种 ·具有饱和性，不易氧化、加成 $ Thiele 1899 1
1 Chapter 4 Aromatic hydrocarbon Prepared by Yang R. L. 苯型芳香烃 非苯型芳香烃 单环 (苯及同系物) 稠环 Aromatic hydrocarbon* 芳香烃 Prepared by Yang R. L. Discovery of benzene* (苯) • 1825 由Michael Faraday从煤焦油中分得， 确定 C:H 为1:1 • 1834由Eilhard Mitscherlich合成，确定分子 式为C6H6 • 类似具有高C:H的化合物也具有芳香气味， 因此称为芳香化合物 Prepared by Yang R. L. Physical properties of benzene • Colorless liquid • b.p. 80.08°C m.p. 5.48°C • Density 0.880g/cm3 • Insoluble in water and soluble in oils and fats Prepared by Yang R. L. Properties of benzene • 分子式 C6H6 • 六个H完全相同 • 一个单取代物，二、三、四取代物各有三 种，五、六取代物各有一种 • 具有饱和性，不易氧化、加成 Prepared by Yang R. L. Dewar benzene 1866~1867 Ladenburg prismane 1869 Kekul'e 1865 Armstrong & Baeyer 1887~1888 Thiele 1899 Proposed structures of benzene
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) 2
2 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)
Nomenclature Nomenclature CH, CH, CH CH NO CH. CH. O.N CH, 邻二甲苯 1,2-二甲基-4-溴苯 1,4-二硝基-2-氯苯 间二甲苯 CH; (o-xylene) (4-bromo-1,2- (2-chloro-1,4- (m-xylene) 对二甲苯 dimethylbenzene) dinitrobenzene) (p-xylene) Nomenclature Aryl CH OH O.N 苯基(phenyl) 苄基(benzyl) NO2 2,6-二溴苯酚 2,4,6-三硝基甲苯 (2,6-dibromophenol) (2.4.6-trinitrotoluene) Physical properties Reactions ·苯及其取代物均不溶于水 ·Electrophilic substitution*(亲电取代) ·大多比水轻 ·Free radical substitution(自由基取代) ·易燃，有毒 ·Oxidation(氧化反应) ·Reduction(还原反应) 3
3 Prepared by Yang R. L. CH3 CH3 CH3 CH3 CH3 CH3 邻二甲苯 (o-xylene) 间二甲苯 (m-xylene) 对二甲苯 (p-xylene) Nomenclature Prepared by Yang R. L. Br CH3 CH3 1 2 3 4 Cl NO2 O2N 1 2 3 4 1,2-二甲基-4-溴苯 (4-bromo-1,2- dimethylbenzene) 1,4-二硝基-2-氯苯 (2-chloro-1,4- dinitrobenzene) Nomenclature Prepared by Yang R. L. CH3 NO2 NO2 O2N 1 2 3 4 5 6 2,4,6-三硝基甲苯 (2,4,6-trinitrotoluene) OH Br Br 1 2 3 4 5 6 2, 6-二溴苯酚 (2,6-dibromophenol) Nomenclature Prepared by Yang R. L. Aryl 苯基 (phenyl) 苄基 (benzyl) Prepared by Yang R. L. Physical properties • 苯及其取代物均不溶于水 • 大多比水轻 • 易燃，有毒 Prepared by Yang R. L. Reactions • Electrophilic substitution* (亲电取代) • Free radical substitution (自由基取代) • Oxidation (氧化反应) • Reduction (还原反应)
Electrophilic substitution* General mechanism ·Halogenation*(卤代反应) Sirp Atack on the elecophite foems the sigm complex. ·Nitration*(硝化反应) HH ·Sulfonation*(磺化反应) ·Friedel--crafts reaction(傅-克反应) HH General mechanism Energy diagram 吸热 +Y-Z [的 mg作ftm Halogenation* Mechanism of halogenation -+RC→0-处-eC FeCl or Fe +C HCI 55-60℃ - % FeBr;or Fe + +Br2- +HBr △ HB" 4
4 Prepared by Yang R. L. Electrophilic substitution* • Halogenation* (卤代反应 ) • Nitration* (硝化反应 ) • Sulfonation* (磺化反应 ) • Friedel-crafts reaction (傅-克反应 ) Prepared by Yang R. L. General mechanism Prepared by Yang R. L. H H H H B H H E [ ] ´ General mechanism Prepared by Yang R. L. Potential-energy diagram describing the course of the reaction of bezene with an eletrophile 吸热 Energy diagram Prepared by Yang R. L. Cl Cl2 55~60。C + FeCl3 or Fe + HCl Br Br + 2 FeBr3 or Fe + HBr Halogenation* Prepared by Yang R. L. Mechanism of halogenation
Energy diagram for bromination Nitration* HONO. H,SO +H,0 6-N0,0s0R:·No,一N02+H 加本 nitiic add +国 444 ReAi41.nlalae .-Cm Sulfonation* Sulfonation* H2SO4 SO,H +S02= △ 0.9 0: +os00 0- +-S0,0H Friedel-crafts reaction Nitration of toluene Toluene reacts 25 times faster than benzene -R+HCI The product mix contains mostly ortho and para substituted molecules 之殿 CH 5
5 Prepared by Yang R. L. Energy diagram for bromination Prepared by Yang R. L. H2 SO4 NO2 + HONO2 + H2O Nitration* Prepared by Yang R. L. SO3 SO3H + H2SO4 Sulfonation* Prepared by Yang R. L. Sulfonation* Prepared by Yang R. L. Friedel-crafts reaction + RCl R AlCl3 + HCl R Cl O C O R AlCl3 + + HCl Prepared by Yang R. L. Nitration of toluene • Toluene reacts 25 times faster than benzene • The product mix contains mostly ortho and para substituted molecules