1、Cycloalkanes第四章第四章 環(huán)烷烴環(huán)烷烴Organic Chemistry A (1)By Prof. Li Yan-MeiTsinghua University 4.1 Classification, Isomerization and nomenclature 4.2 Structure of cycloalkanes 4.3 Physical properties & spectrum data 4.4 Chemical properties 4.5 Preparation (learn on your own) 4.1 Classification, Isomeriz

2、ation and nomenclature 4.1.1 Classification 4.1.2 Isomerism 4.1.3 Nomenclature4.1.1 ClassificationBy the size of the ring 按環(huán)的大小按環(huán)的大小Small ringsMedium ringsCommon ringsLarge ringsC3C4C8C12C5C7C13By the saturation 按不飽和度按不飽和度CnH2nCnH2n-2CnH2n-4Cycloalkanes 環(huán)烷環(huán)烷Cyclo olefines 環(huán)烯環(huán)烯Cyclo alkynes 環(huán)炔環(huán)炔Monoc

3、yclic compounds 單環(huán)單環(huán)By the number of the rings 按環(huán)的數(shù)目按環(huán)的數(shù)目Polyring compounds 多環(huán)多環(huán)Fused ring 稠環(huán)稠環(huán)Bridged ring 橋環(huán)橋環(huán)Spiro rings 螺環(huán)螺環(huán)兩環(huán)之間共用一個(gè)兩環(huán)之間共用一個(gè)碳原子碳原子兩環(huán)之間共用一根共兩環(huán)之間共用一根共價(jià)鍵（共用兩個(gè)直接價(jià)鍵（共用兩個(gè)直接相連的碳原子）相連的碳原子）兩環(huán)之間共用兩個(gè)兩環(huán)之間共用兩個(gè)不直接相連的碳原不直接相連的碳原子子螺原子橋頭碳To define the number of the rings:The number of cutting you

4、need to get a chain molecule out of a poly ring compound幾環(huán)？將橋（稠）環(huán)烴變?yōu)殒湢罨衔飼r(shí)需要斷裂的碳鏈將橋（稠）環(huán)烴變?yōu)殒湢罨衔飼r(shí)需要斷裂的碳鏈數(shù)。如需斷裂兩次，則為二環(huán)化合物，斷裂三次則數(shù)。如需斷裂兩次，則為二環(huán)化合物，斷裂三次則為三環(huán)化合物。為三環(huán)化合物。Some interesting bridging compoundsCubane立方烷立方烷Primane棱棱 烷烷Diamentane金剛烷金剛烷籃籃 烷烷4.1.2 Isomerism Constitutional isomers are derivated from t

5、he change of size of rings and length of side chainsC5H10環(huán)的大小及側(cè)鏈長(zhǎng)短與位置變化環(huán)的大小及側(cè)鏈長(zhǎng)短與位置變化4.1.3 Nomenclature 命名命名4.1.3.1 Monocyclic alkane 單環(huán)烷烴單環(huán)烷烴1, When the side chain is not very complicate: 當(dāng)支鏈不復(fù)雜時(shí)，以環(huán)烷烴為母體當(dāng)支鏈不復(fù)雜時(shí)，以環(huán)烷烴為母體methylcyclopentane2-ethyl-4-methyl-1-propylcycloheptane1-ethyl-3-methylcyclopenta

6、ne1,2-dimethylcyclopentane1,2-二甲基環(huán)戊烷二甲基環(huán)戊烷甲基環(huán)戊烷甲基環(huán)戊烷1-甲基甲基-3-乙基乙基環(huán)戊烷環(huán)戊烷4-甲基甲基-3-乙基乙基-1-丙基環(huán)己烷丙基環(huán)己烷2, When the side chain is complicate or difficult to name: 當(dāng)支鏈較復(fù)雜或不易命名時(shí)，以環(huán)烷基為取代基當(dāng)支鏈較復(fù)雜或不易命名時(shí)，以環(huán)烷基為取代基3-cyclohexylhexane3-環(huán)己基己烷環(huán)己基己烷3, When two rings are connected 兩環(huán)相連時(shí)兩環(huán)相連時(shí)Cyclopropylcyclohexane環(huán)丙基環(huán)己烷環(huán)丙

7、基環(huán)己烷Cyclopropylcyclopropane環(huán)丙基環(huán)丙烷環(huán)丙基環(huán)丙烷4, Cis and trans isomerism:CH3CH3HHCH3HCH3HCH3CH3CH3CH3Cis-1,4-dimethylcyclohexaneTrans-1,4-dimethylcyclohexaneHow to name this compound ?CH3CH3CH34.1.3.2 Polyring alkane 多環(huán)烷烴多環(huán)烷烴1, Spiro cycloalkanes 螺環(huán)烴螺環(huán)烴123456789101“小原則”：在不違背螺環(huán)烴命名的“大”原則基礎(chǔ)上，在編號(hào)時(shí)應(yīng)盡可能令取代基的位號(hào)最小

8、。12345678910思考！12345678910spiro4.5decane螺螺4.5癸烷癸烷spiro5.5undecane螺螺5.5十一烷十一烷123456789106-methylspiro4.5decane6-甲基甲基4.5癸烷癸烷4-methylspiro2.4heptane4-甲基甲基2.4庚烷庚烷2, Bridged-ring alkane and fused-ring alkane 橋環(huán)烴和稠環(huán)烴橋環(huán)烴和稠環(huán)烴12345678bicyclo3.2.1octane二環(huán)二環(huán)3.2.1辛烷辛烷2,7,7-trimethylbicyclo2.2.1heptanebicyclo1.1

9、.0butane2,7,7-三甲基二環(huán)三甲基二環(huán)2.2.1庚烷庚烷注意：有兩個(gè)橋頭碳可注意：有兩個(gè)橋頭碳可供選擇供選擇二環(huán)二環(huán)1.2.0丁烷丁烷For polycyclic compound as following 多元環(huán)多元環(huán)Deciding the main ring 選選“主環(huán)主環(huán)”：最大的環(huán)：最大的環(huán)Choosing the main bridged carbon 選選“主橋頭碳主橋頭碳”：主環(huán)與非主環(huán)的最長(zhǎng)橋共用的橋頭碳：主環(huán)與非主環(huán)的最長(zhǎng)橋共用的橋頭碳Decide the serial number 編號(hào)：從主橋頭碳開始；從最長(zhǎng)橋開始編號(hào)：從主橋頭碳開始；從最長(zhǎng)橋開始Naming

10、 the compound 書寫（注意與非主橋相連的橋需注明所連橋的編號(hào)）書寫（注意與非主橋相連的橋需注明所連橋的編號(hào)）1234567Tricyclic2.2.1.02.6heptane思考：12345678910Tricyclic3.2.2.12.7decanetricyclic3.2.2.12.7dacaneFused ringnaphthaleneHydrogenated naphthaleneEndo/exaOHHendoHOHexa區(qū)別：母體！區(qū)別：母體！ 4.2.1 Baeyers strain theory 4.2.2 Heat of combustion for cycloal

11、kane 4.2.3 Current opinions 4.2.4 Conformations of cyclohexane 4.2.5 Configuration of decalin4.2 Structure of cycloalkanesBefore 18801883Only penta rings and hexa rings were found. It was regarded that rings smaller than penta rings and bigger than hexa rings do not exist, or are not stable.W.H.Perk

12、in synthesized C3, C4, and identified the relative reactivity: double bond C3 C4 ,while C5 and C6 rings are relatively more stable.1885A.von.Baeyer put forward the strain theory4.2.1 Baeyers strain theory Bayers張力學(xué)說(shuō)張力學(xué)說(shuō)Assumption:1, carbon atoms in the ring are on the same plane; 成環(huán)的碳原子均在同一同面上，且呈正多邊

13、形成環(huán)的碳原子均在同一同面上，且呈正多邊形2, carbon atoms are sp3 carbon atoms; 碳原子采取碳原子采取sp3雜化形式，正常鍵角應(yīng)為約雜化形式，正常鍵角應(yīng)為約109.5度度3, to meet some special angles in the ring, the bonds have to be bending; 為了滿足平面正多邊形的內(nèi)角要求，成環(huán)的鍵必須向內(nèi)或向外為了滿足平面正多邊形的內(nèi)角要求，成環(huán)的鍵必須向內(nèi)或向外“屈撓屈撓”， “ “屈撓屈撓”的程度越大，體系越不穩(wěn)定。的程度越大，體系越不穩(wěn)定。More bendingMore angle stra

14、inHigher energyLess stability60o90o108o120o129oMost stable?可解釋一些體系的穩(wěn)定性特點(diǎn)，但還有一些體系無(wú)法解釋。 4.2.2 Heat of combustion for cycloalkane Heat of combustion per CH2kJ/mol697686664659662n658Do not fit the strain theory!p 角張力（Baeyer 張力）p 扭轉(zhuǎn)張力p 范氏力影響環(huán)體系穩(wěn)定性的主要因素： 4.2.3 Current opinionsCCC105.5oCCCBent Bond （彎曲鍵、香蕉

15、鍵）（彎曲鍵、香蕉鍵）角張力：角張力：109.50-105.50=4012HHHH12CH233扭轉(zhuǎn)張力：扭轉(zhuǎn)張力：三組三組HCC均處于全重疊式均處于全重疊式HHHHHHHHHHHHHHHHA nonplanar conformation 非平面構(gòu)象非平面構(gòu)象 也存在彎曲鍵也存在彎曲鍵 111.50角張力：角張力：111.50109.50 = 20123HHH2CH2CHH4部分交叉式部分交叉式扭轉(zhuǎn)張力較小扭轉(zhuǎn)張力較小6.3kJ/mol higher全重疊式全重疊式2.5kJ/molenvelop structurehalf-chair structure信封式 半椅式具有多組全重疊式具有多組

16、全重疊式Large ring多于多于13個(gè)碳原子的環(huán)體系中，分子鏈一般呈皺折形個(gè)碳原子的環(huán)體系中，分子鏈一般呈皺折形Strain energy in cycloalkanesNameAngle strainTwist strainVan de waalsC3GreatMediumNoC4GreatMediumNoC5SlightMediumNoC6NoNoNoC7C12MediumMediumGreatC12NoNoNo4.2.4 Conformations of cyclohexaneYearName of scientistPoint of view1883BaeyerAssumes th

17、at six carbon atoms are on the same plane1890H.SachseTwo conformations may exist1915-1918W.M.MohrChair model and boat model1920Cyclohexane was proved to be nonplanar experimentally1943O.HasselChair model is most stable(electron diffraction method)1950D.BartonConformation analysis of cyclohexaneA his

18、tory4.2.4.1 Conformation of cyclohexane250pmC350pmChair Structure 椅式椅式123456123HHH2CCH2HH465HHHH部分交叉式，扭轉(zhuǎn)張力較小部分交叉式，扭轉(zhuǎn)張力較小Axial bondEquatorial bondTwo types of C-H bonds in chair structurea 鍵鍵e 鍵鍵Boat structure 船式結(jié)構(gòu)船式結(jié)構(gòu)183pmVan de waal radius of H atom is 120pm, so the two adjacent hydrogen atoms caus

19、es serious excluding.存在范氏力存在范氏力123456HHHH651HH2CHHHH2C423全重疊式，存在扭轉(zhuǎn)張力全重疊式，存在扭轉(zhuǎn)張力2、3、5、6碳處于同一平面碳處于同一平面Flagpole interactionTwist boat structure 扭船式扭船式HHHHHHHHHHHH123456123456123456Half chair structure 半椅式半椅式123456123456Potential energy of the conformations 各種構(gòu)象勢(shì)能關(guān)系圖各種構(gòu)象勢(shì)能關(guān)系圖46kJ/molPotential energy pro

20、cess 椅式構(gòu)象之間的轉(zhuǎn)變：46kJ/molPotential energyReaction process4.2.4.2 mono substituted cyclohexane CH3HCH3H250pmr.t.5 95 Reason 1: Van de waals forcesAtomHCH2CH3NPOR/pm120200200150190140AtomSFClBrIR/pm185135180195215CH3HCH3H250pmr.t.1,3二直立鍵二直立鍵相互作用相互作用6116Reason 2: Torsional strain162HHCCH3CH5a 鍵162CHHCCH3

21、H5CH3HCH3He 鍵6161結(jié)論與推論：結(jié)論與推論：1、一取代時(shí)，取代基趨向于處于、一取代時(shí)，取代基趨向于處于e鍵鍵2、若有多個(gè)取代基，在滿足順?lè)礃?gòu)型關(guān)系的前提下，、若有多個(gè)取代基，在滿足順?lè)礃?gòu)型關(guān)系的前提下，則越多取代基處于則越多取代基處于e鍵時(shí)越穩(wěn)定。鍵時(shí)越穩(wěn)定。3、若環(huán)上有不同取代基，在滿足順?lè)礃?gòu)型關(guān)系的前提、若環(huán)上有不同取代基，在滿足順?lè)礃?gòu)型關(guān)系的前提下，則大基團(tuán)處于下，則大基團(tuán)處于e鍵時(shí)較穩(wěn)定。鍵時(shí)較穩(wěn)定。4.2.4.3 double substituted cyclohexane (same groups)a 鍵鍵e 鍵鍵a鍵、鍵、e鍵的順?lè)搓P(guān)系鍵的順?lè)搓P(guān)系Cis-1,2tr

22、ans-1,2trans-1,31,1cis-1,3cis-1,4trans-1,44.2.4.4 double substituted cyclohexane (different groups)u Conformation with all groups on e bond is most preferred; 在滿足空間構(gòu)型的前提下，令盡可能多的取代基處于在滿足空間構(gòu)型的前提下，令盡可能多的取代基處于e鍵。鍵。u If the above condition can not be met, the group with a bigger size is on the e bond. 優(yōu)先

23、滿足大基團(tuán)處于優(yōu)先滿足大基團(tuán)處于e鍵。鍵。-F, -CN -Cl, -Br, -I -OCH3 -OH -COOH -NH2 -CH3 -CH2CH3 -CH(CH3)2 -C6H5 -C(CH3)3 注：注：1、OH，NH2易受溶劑的影響，尤其是形成氫鍵時(shí)。易受溶劑的影響，尤其是形成氫鍵時(shí)。 2、此順序應(yīng)用于、此順序應(yīng)用于1,2取代時(shí)可能有誤差。取代時(shí)可能有誤差。練習(xí)：畫出以下結(jié)構(gòu)的最穩(wěn)定構(gòu)象練習(xí)：畫出以下結(jié)構(gòu)的最穩(wěn)定構(gòu)象ButCH3ButH3CButCH3ButCH3ButCH3ButCH3ButH3C4.2.5 Configuration of decalin 十氫合萘的構(gòu)型十氫合萘的構(gòu)

24、型HHHH8.7kJ/mol more stable4.3 Physical properties & spectrum data物理性質(zhì)： 環(huán)烷烴分子較規(guī)則，不易自由搖動(dòng) 分子排列緊密 熔點(diǎn)、沸點(diǎn)、密度等一般高于相應(yīng)的直鏈烷烴HHa-He-HTheoretically, e-H is 0.20.5 ppm larger than a-H . But due to the fast transform of cyclohexane, this difference is often invisible.1H-NMR環(huán)烷烴中環(huán)烷烴中CH2的的CH伸縮振動(dòng)受環(huán)張力的影響，波數(shù)伸縮振動(dòng)受環(huán)張力的影響，波數(shù)升高，強(qiáng)度下降。升高，強(qiáng)度下降。五元以下小環(huán)的亞甲基伸縮振動(dòng)波數(shù)均大于五元以下小環(huán)的亞甲基伸縮振動(dòng)波數(shù)均大于3000cm-1，大，大于五元的環(huán)則與直鏈烷烴一樣。于五元的環(huán)