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2.5NomenclatureofAlkanesinChineseCommonnomenclature:CH3CH2CH2CHCH3CH3IsohexaneIUPACNomenclature:P.46,InternatinalUnionofPureandAppliedChemistryNo.ofCarbonsFormulaName(CnH2n+2)1MethaneCH42EthaneC2H63PropaneC3H84ButaneC4H105PentaneC5H126HexaneC6H147HeptaneC7H168OctaneC8H189NonaneC9H2010DecaneC10H22NamesofSmallHydrocarbonsGreeknumbers-aneAlkylGroups•Alkylgroup–removeoneHfromanalkane(apartofastructure)•Generalabbreviation“R”•Name:replace-aneendingofalkanewith-ylending(SeeEng.P.44and45forlists)AlkanesAlkylgroupAbbreviationCH4MethaneCH3MethylMeCH3CH3CH3CH2EtEthaneEthylCH3CH2CH3CH3CH2CH2PrPropanePropylCH3CH2CH2CH3CH3CH2CH2CH2ButaneButylBuTypesofAlkylgroupsClassifiedbytheconnectionsiteacarbonattheendofachain(primaryalkylgroup)acarboninthemiddleofachain(secondaryalkylgroup)acarbonwiththreecarbonsattachedtoit(tertiaryalkylgroup)CCHHCCHCCCCCCHCH3CH3CH2CH3CH3CHCHCH3CH3CH2CH3CCH3CH3Isopropylsec-butyl(orsec-Bu)Isobutyltert-butylort-Butyl,t-Bu)AlkylgroupsNamePrefixParentSuffixWherearethesubstituents?HowmanyCarbons?WhatFamily?NamingBranchedchainAlkanes-IUPACP47,2.3Step1FindtheparenthydrocarbonFindthelongestcontinuouschainofcarbonatomsCHCHCHCH2CH2CH3CH3CH3CH3CHCH3CH2CH3CHCHCHCH2CH2CH3CH3CH3CH3CHCH3CH2CH3Toequallongchains,choosethechaincontainingthemostbranchedchain.HeptaneStep2NumbertheatomsinthemainchainBeginningattheendnearerthefirstbranchpoint,numbereachCatomintheparentchain.CH3CH2CHCHH3CCH2CH2CH3CH2CH312356741235674CH3CH2CHCHH3CCH2CH2CH3CH2CH3NOT3.DesignatethelocationofthesubstituentsCH3CH2CH2CHCHCH2CH2CHCH3CH3CH2CH2CH3CH2CH31234756894-Isopropyl-5-propylnonane•Listthesubstituentsinalphabeticalorder.•Whenthesamesubstituentsappearsmorethanonce,usethemultiplyingprefixes:di-,tri-,tetra-andsoon.CCH2CHCH3CH3CH3CH3CH32,2,4-Trimethylpentane4-Ethyl-3,5-dimethyloctaneCH3CH2CHCHCHCH2CH2CH3CH3CH3CH2CH32.6PropertiesofAlkanesP49self-studyafterclass2.7Conformation构象ofAlkanesConformation:DifferentspatialarrangementsofatomsoratomicgroupsinamoleculethataregeneratedbyrotationaboutC－Csinglebond.Eng.p502.51.ConformationalAnalysisofEthaneNewmanProjectionSawhorserepresentationEclipsedconformationHHHHHHHHHHHHStaggeredconformationHHHHHHHHHHHH3.1NomenclatureofAlkenesIUPACNames:1.Givetheparentnamebyselectingthelongestcontinuouscarbonchainincludingthedoublebond.Ethylene,propylene,butene,pentene…suffix-eneii:[英][‵prəupili:n][美][‵propə﹐lin]2.Number:Givethedouble-bondcarbonsthelowernumber.3.locatethesubstituentslikealkanes.CCCH3CH2CH3CH2CH2HH2-Ethyl-1-penteneCH3CH34,4-Dimethylcycloheptene2-乙基-1-戊烯4.Beforetheparentname,listthepositionofdoublebondCCCH3CH2CH3CH2CH2HH2-Ethyl-1-pentene1可以不标出来Alkenylgroups:VinylAllyl(Allylicgroup)烯丙基CH3CHCHCH2CHCH2CHCH2Propenyl丙烯基CH2CCH3Isopropenylei3.2StructureofAlkenesEthylene:sp2HybridorbitalsP13,1.9Groundstate2p2s1sPromotionofelectronExitedstate2p2s1ssp2-hybridizedstate1s2psp2Hybri-dizationAnsp2orbital1/3sorbital2/3porbitalThreeequivalentsp2hybridorbitalslieinaplaneatangleof120°tooneanother.GeometricstructureofCatomwithsp2-hybrid:PlanartriangleAsingleunhybridizedporbitalperpendiculartothesp2plane.TheformationofC-Cπbond:2p-2psidebysideoverlap.TheformationofC-Hσbond:sp2-1soverlap.OneC-Cσbondand4C-Hσbondarecoplanar.TheformationofC-Cπbond:2p-2psidebysideoverlap.InthemoleculeofEthylene:TheformationofC-Cσbond:sp2_sp2overlapporbitaloverlapHHHHσ-bondporbitaloverlapCCσbondπbondCarbon-carbondoublebondModelsofEthylene3.3IsomerisminAlkenesP79,3.3CCHHHCH2CH3CCHCH3HCH3CCH3CHHCH3CCH3CHHCH31-Butene2-MethylpropyleneIsobutenecis-2-Butenetrans-2-ButeneConstitutionalisomers(I)(III)(IV)(II)(I)(II)(III)(IV)Stereoisomers(III)(IV)Cis-transisomers构造异构:原子连接顺序立体异构:空间cis-2-Butenetrans-2-ButeneRotationaboutC-CdoublebondisrestrictedConfigurationNamingStereoisomericAlkenes1.NamingbytermCis-transThesameatomsoratomicgroupsonthesamesidesontheoppositesidesofthedoublebond.Prefixcis-trans-TodisubstitutedAlkenes:P79,3.32.NamingbytheE,ZsystemCCHCH2CH2CH3H3CCH3CCClHBrCH2CH3Readingtext:keypointfromP81,3.4tillP.83practiceproblem3.310minP813.4E,ZsystembaseonanSequenceRule－Cahn-Ingold-PrelogpriorityRule1.Consideringeachofthedouble-bondedcarbon,identifythetwoatomsdirectlyattachedandrankthemaccordingtoatomicnumber.CCClHBrCH2CH3BrCl,CHLowpriorityHighpriority(E)-1-Bromo-1-chloro-1-buteneLowpriorityHighpriorityEconfiguration:thehigh-prioritygroupsareontheoppositesidesofthedouble-bondZconfiguration:thehigh-prioritygroupsareonthesamesidesofthedouble-bond2.Whentwoatomsdirectlyattachedtothedoublebondareidentical,lookatthesecond,third,orfourthatomsawayfromthedouble-bondedcarbonsuntilthefirstdifferenceisfound.CCHCH2CH2CH3H3CCH3(Z)-3-methyl-2-hexeneCHHHCCHHHHHCHCH3CH3CCH3HHOHCHHHO3.Multiple-bondedatomsareequivalenttothesamenumberofsingle-bondedatoms.COHCHOOThecarbonisbondedtoH,O,OThecarbonisbondedtoH,C,CCCHHHCHCCCHHHydrocarbonscontainingacarbon-carbontriplebond.Eng.P128R'CCR4.13Alkynes•Suffix:aneyneNomenclatureCCH2CH3HC1-ButyneaiNumberingstartsfromtheendneartriplebond.1-丁炔StructureofAlkynesAcetylene(ethyne):spHybridorbitalsC:Groundstate2p2s1sPromotionofelectronExitedst