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1、第五章 芳香烃 Aromatic pounds,概述,1.脂肪烃及芳香烃,Aliphatic and aromatic pounds芳香性 Aromaticity,+Br2/CCl4,+Br2/FeBr3,KMnO4,Aromaticity 芳香性稳定的环，易取代，难加成，难氧化,？,2.烷基苯工业来源（Industrial source of alkylbenzenes）,CoalPetroleum（见书第四节）,Coal,（no air),Coke(焦炭）,Coal tar(煤焦油)+Coal gas,Benzene,toluene,xylenes,phenol,cycloalkanes,
2、Aromatic hydrocarbon,Catalytic reforming催化重整,馏分名称 沸点范围/主要成分 轻油 360 沥青、游离碳,煤焦油的分馏产物,3.分类,单环芳烃 多环芳烃 非苯芳烃,第一节 单环芳烃,苯及同系物（benzene and homolog）,一.苯的结构（structure of benzene）,1.开库勒结构式（Kekule structure）In 1825 M.FaradayIn 1834 E.MitscherlichIn 1865 August Kekule,August Kekule,I was sitting writing at my tex
3、tbook,but the work did not progress;my thoughts were elsewhere.I turned my chair to the fire,and dozed.Again the atoms were gamboling before my eyes.This time the smaller groups kept modestly in the beckground.My mental eye,rendered more acute by repeated visions of this,kind,could now distinguish l
4、arger structures of manifold conformations;long rows,sometimes more closely fitted together;all twisting and turning in snake-like motion.But look!What was that?One of the snakes had seized hold of its own tail,and the form whirled mockingly before my eyes.As if by a flash of lightning I woke;I spen
5、t the rest of the night working out the consequences of the hypothesis.Let us learn to dream,gentlemen,and then perhaps we shall learn the truth.,August Kekule,苯环结构的诞生是有机化学发展史上的一块里程碑,Kekule formula,Dewar formula,2.轨道理论Theory of orbit,C SP2,（1）C sp2 hybridized（2）Particularly stable（3）电子离域 Electron De
6、localization,CH3CH3 Csp3-Csp3 154 pmCH2=CHCH3 Csp2-Csp3 150 pmCH2=CHCH=CH2 Csp2-Csp2 146 pmC6H6 Csp2-Csp2 139 pm,3.分子轨道理论Theory of molecular orbit,4.共振（Resonance structure of benzene）,Resonance Contributors,Linus pauling,电子离域与共振Electron Delocalization and Resonance,上述非经典结构式较好地表示了电子的离域，但是却无法告诉我们该结构中含
7、有多少双键。因此化学家常用共振结构（共振极限结构）来表示。,p-electrons in conjugated dienes and benzene are delocalized定域电子：被限制在两个原子核区域内运动的电子离域电子：不局限于两个原子核区域内运动的电子这种电子的离域作用我们也称之为共轭作用,How to drow resonance contributors,Rules for Drawing Resonance ContributorsOnly electrons move.The nuclei of the atoms never moveThe only electron
8、s that can move are electrons and nonbonding electronsThe total number of electrons in the molecule does not change,neither do the numbers of paired and unpaired electrons,In order to draw contributors,the electrons in one resonance contributor are moved to generate the next contributor.,The electro
9、ns can be moved in one of the following ways,（1）Move electrons toward a positive charge,（2）Move electrons toward a bond,（3）Move a nonbonding pair of electrons toward a bond,（4）Move a single nonbonding electron toward a bond,共振杂化体比它的任何一个共振式都要稳定共价键数目越多的共振式越稳定共振式中的电荷越分散就越稳定越稳定的共振式对共振杂化体的贡献越大,1,3-butadi
10、ene,（5）相对稳定的共振式的数目越多，共振杂化体越稳定,（6）共振式越接近等价，共振杂化体越稳定,二.命名 Nomenclature,1.简单 苯（benzene）,Chlorobenzene Nitrobenzene,Special names,Toluene Aniline,2.相对复杂,2-苯基戊烷2phenylpentane,苯乙烯Styrenephenylethylene,3.多取代基,O-Dibromobenzene ortho,m-Dibromobenzene meta,p-Dibromobenzene para,2-氯-3-硝基苯磺酸2-chloro-3-nitrobenz
11、ene-sulfonicacid,优先次序：-COOH，-SO3H，-CN，-CHO，C=O，-OH，-NH2，-R，-X，NO2,三、物理性质,苯：无色透明,易燃液体。不溶于水。遇热、明火易燃烧、爆炸。能与氧化剂,发生剧烈反应。蜡、树脂、油的溶剂;合成化学制品和制药的中间体。汽油一种成份,含量2%急性苯中毒：麻醉作用慢性中毒,四、化学性质,（一）芳香亲电取代反应（electrophilic aromatic substitution reactions）,+Br2/FeBr3,Step 1:,Step 2:,：,机理 Mechanism:,Step 1:,Reaction coordinat
12、e diagrams:,1.卤代 Halogenation,Catalyst:FeCl3,AlCl3,CuCl2,SbCl5,Bromobenzene,FeBr3+Br2 FeBr4-+Br+,diazepam,2.硝化 Nitration,Nitrobenzene,硝基苯,硝基苯;密斑油;苦杏仁油相对密度1.205。难溶于水硝基苯的主要毒作用,3.磺化 Sulfonation reversible reaction,苯磺酸 Benzenesulfonic acid,sulfanilimide,prontosil,磺胺甲噁唑（sulfamethoxazole，sinomin，SMZ）又名新诺明
13、,噁唑 异噁唑,4.傅-克烷基化反应(Friedel-Crafts Alkylation),傅瑞尔克拉夫茨,CFriedel 1832-1899J.A.Crafts 1839-1917,Note:,催化剂 Catalyst:Lewis acids,AlCl3,FeCl3,ZnCl2,SnCl4,BF3 重排Rearrangement may occur in alkylation,10,10,多元取代物 polysubstitutionLimitation,Aromatic rings containingthe,group do not undergo F-C Alkylation,polyhalogenated alkanes？,alcohol,alkene,5.傅-克酰基化反应(Friedel-Crafts Acylation),没有重排问题,5个亲电取代反应,亲电试剂electrophile：,Cl-Cl+-AlCl3 Br-Br+-FeBr3+NO2(obtained by HNO3+H2SO4)+SO3H(from H2SO4)or SO3 R+(obtained by R-Cl+AlCl3)RC+=O(obtained by RCOCl+AlCl3),思考题：如何从苯合成正丁基苯？,
