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1、第五章 芳香烴 Aromatic compounds,概述,1.脂肪烴及芳香烴,Aliphatic and aromatic compounds 芳香性 Aromaticity,+Br2/CCl4,+Br2/ FeBr3,KMnO4,Aromaticity 芳香性 穩(wěn)定的環(huán)，易取代，難加成，難氧化,？,2.烷基苯工業(yè)來(lái)源（ Industrial source of alkylbenzenes ）,Coal Petroleum （見(jiàn)書第四節(jié)）,Coal,（no air),Coke(焦炭）,Coal tar(煤焦油)+ Coal gas,Benzene,toluene,xylenes,phenol

2、,cycloalkanes,Aromatic hydrocarbon,Catalytic reforming 催化重整,餾分名稱 沸點(diǎn)范圍/ 主要成分 輕油 360 瀝青、游離碳,煤焦油的分餾產(chǎn)物,3.分類,單環(huán)芳烴 多環(huán)芳烴 非苯芳烴,第一節(jié) 單環(huán)芳烴,苯及同系物（ benzene and homolog ）,一.苯的結(jié)構(gòu) （structure of benzene）,1.開庫(kù)勒結(jié)構(gòu)式（ Kekule structure） In 1825 M.Faraday In 1834 E.Mitscherlich In 1865 August Kekule,August Kekule,I was si

3、tting writing at my textbook,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

4、,could now distinguish larger 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

5、 lightning I woke;I spent 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,苯環(huán)結(jié)構(gòu)的誕生是有機(jī)化學(xué)發(fā)展史上的一塊里程碑,Kekule formula,Dewar formula,2.軌道理論Theory of orbit,C SP2,（1） C sp2 hybridized （2） Particular

6、ly stable （3）電子離域 Electron Delocalization,CH3CH3 Csp3-Csp3 154 pm CH2=CHCH3 Csp2-Csp3 150 pm CH2=CHCH=CH2 Csp2-Csp2 146 pm C6H6 Csp2-Csp2 139 pm,3.分子軌道理論Theory of molecular orbit,4.共振（ Resonance structure of benzene ）,Resonance Contributors,Linus pauling,電子離域與共振 Electron Delocalization and Resonance

7、,上述非經(jīng)典結(jié)構(gòu)式較好地表示了電子的離域，但是卻無(wú)法告訴我們?cè)摻Y(jié)構(gòu)中含有多少雙鍵。因此化學(xué)家常用共振結(jié)構(gòu)（共振極限結(jié)構(gòu)）來(lái)表示。,p-electrons in conjugated dienes and benzene are delocalized 定域電子：被限制在兩個(gè)原子核區(qū)域內(nèi)運(yùn)動(dòng)的電子 離域電子：不局限于兩個(gè)原子核區(qū)域內(nèi)運(yùn)動(dòng)的電子 這種電子的離域作用我們也稱之為共軛作用,How to drow resonance contributors,Rules for Drawing Resonance Contributors Only electrons move. The nuclei

8、of the atoms never move The only electrons that can move are electrons and nonbonding electrons The 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 t

9、o generate the next contributor.,The electrons 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,共振雜化體比它的任何一個(gè)共振式都要穩(wěn)定 共價(jià)鍵數(shù)目越多的

10、共振式越穩(wěn)定 共振式中的電荷越分散就越穩(wěn)定 越穩(wěn)定的共振式對(duì)共振雜化體的貢獻(xiàn)越大,1, 3-butadiene,（5）相對(duì)穩(wěn)定的共振式的數(shù)目越多，共振雜化體越穩(wěn)定,（6）共振式越接近等價(jià)，共振雜化體越穩(wěn)定,二.命名 Nomenclature,1. 簡(jiǎn)單 苯 （ benzene）,Chlorobenzene Nitrobenzene,Special names,Toluene Aniline,2. 相對(duì)復(fù)雜,2-苯基戊烷 2phenylpentane,苯乙烯 Styrene phenylethylene,3.多取代基,O-Dibromobenzene ortho,m-Dibromobenzene

11、 meta,p-Dibromobenzene para,2-氯-3-硝基苯磺酸 2-chloro-3-nitrobenzene-sulfonicacid,優(yōu)先次序： -COOH ， -SO3H ， -CN ， -CHO，C=O，-OH，-NH2，-R，- X ， NO2,三、物理性質(zhì),苯：無(wú)色透明,易燃液體。 不溶于水。遇熱、明火易燃燒、爆炸。 能與氧化劑, 發(fā)生劇烈反應(yīng)。 蠟、樹脂、油的溶劑; 合成化學(xué)制品和制藥的中間體。汽油一種成份,含量2% 急性苯中毒：麻醉作用 慢性中毒,四、化學(xué)性質(zhì),（一）芳香親電取代反應(yīng) （electrophilic aromatic substitution re

12、actions）,+Br2/ FeBr3,Step 1:,Step 2:,：,機(jī)理 Mechanism:,Step 1:,Reaction coordinate diagrams:,1.鹵代 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 相對(duì)密度1.205。難溶于水 硝基苯的主要毒作用,3.磺化 Sulfonation reversible reaction

13、,苯磺酸 Benzenesulfonic acid,sulfanilimide,prontosil,磺胺甲噁唑（sulfamethoxazole，sinomin，SMZ）又名新諾明,噁唑 異噁唑,4.傅-克烷基化反應(yīng) (Friedel-Crafts Alkylation ),傅瑞爾克拉夫茨,CFriedel 1832-1899 J.A.Crafts 1839-1917,Note:,催化劑 Catalyst:Lewis acids, AlCl3, FeCl3, ZnCl2, SnCl4, BF3 重排Rearrangement may occur in alkylation,10,10,多元取代

14、物 polysubstitutionLimitation,Aromatic rings containing the,group do not undergo F-C Alkylation,polyhalogenated alkanes？,alcohol,alkene,5.傅-克?；磻?yīng) (Friedel-Crafts Acylation ),沒(méi)有重排問(wèn)題,5個(gè)親電取代反應(yīng),親電試劑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),思考題： 如何從苯合成正丁基苯？,