生物化学ChapterSteroChemistry省公共课一等奖全国赛课获奖课件.pptx

Exercises:7.1-7.37.6-7.177.22-7.247.26-7.327.37,7.41第1页Chapter 7 Stereochemistry第2页Stereoisomers:isomersthathavethesameatomsbondedtooneanother(sameconstitution),butdifferent3-Dorientationoftheatomsinspace.Conformationalstereoisomers:interconvertbyrotationaboutabondstaggeredandeclipsedconformersgaucheandanticonformerschair-chairconformersConfigurationalstereoisomers:cantbeinterconvertedcisandtransisomersEandZisomersTwonewones:enantiomers:stereoisomersthatarenonsuperimposablemirrorimagesdiastereomers:stereoisomersthatarenotmirrorimages第3页IsomerConstitutionalIsomersStereoisomersCis-TransIsomersIsomersthatcontainchiralitycentersIsomers:Nonidenticalcompoundshavingthesamemolecularformula第4页Cis-TransIsomers第5页 7.1 Molecular Chirality.EnantiomersEnantiomerism(光学异构现象)Chirality:物体与其镜像不重合性质第6页Whyischiralityimportant?Chiralspeciesfitsinchiralbindingsite(matchedkeyandlock)第7页Chiralspeciesdoesnotfitinbindingsite(mismatchedkeyandlock)第8页第9页(a)StructuresAandBaremirror-imagerepresentationsofbromochlorofluoromethaneAB陈立陈立第10页第11页Enantiomersnonsuperimposablemirror-imagemolecules第12页(b)ReorientBbyturningit180 B =B陈立陈立180第13页(c)Compare A and B.The two do not match.AB第14页lStereoisomersthatarerelatedasanobjectanditsnonsuperposablemirrorimageareclassifiedasenantiomers.(对映异构体)l手性分子(Chiralmolecules)实体与镜象不能重合分子l手性中心(Chiralcenter)：与四个不一样原子或基团相接原子主要有：C,N,S,Pl手性分子特点：分子中一个碳原子与四个不一样原子或基团相连接对应碳原子称之为手性碳(惯用C*表示)AchiralcompoundshavesuperimposablemirrorimagesChiralcompoundshavenonsuperimposablemirrorimages第15页Mirro-imageformsofchloroflouromethanearesuperposable(可置于上面可置于上面,可重合可重合,可叠合可叠合)upononeanother.Chlorodifluoromethaneisachiral.(非手性非手性)第16页Chloroflouromethane第17页第18页DrawingEnantiomersPerspectiveformulaFischerprojection第19页Astereocenter(stereogeniccenter)isanatomatwhichtheinterchangeoftwogroupsproducesastereoisomer第20页7.2 The Stereogenic CenterAstereocenter(stereogeniccenter)isanatomatwhichtheinterchangeoftwogroupsproducesastereoisomer第21页第22页7.3 Symmetry in Achiral StructuresSymmetryAxis对称轴Planeofsymmetry对称面Centerofsymmetry对称中心第23页SymmetryAxis对称轴一条直线经过分子，使分子绕此直线旋转一定角度后而能与原来分子重合直线第24页绕轴转动，转动角度后能与原分子重合，则360/=n为该分子n重对称轴，用Cn表示第25页Plane of symmetry 对称面对称面()：但成份子全部原子都在同一平面上，或平面能够经过分子并将其分成互为镜象两个部分。陈立陈立苯：七个对称面第26页CH2Cl2第27页Center of symmetry 对称中心对称中心(i):经过分子中心与分子中任何一个原子连一直线，然后将此直线问相反方面延长，并在离中心等距处碰到完全相同原子，则此中心是该分子对称中心。Itischaracterisedbyanatomwhichhasdifferentgroupsboundtoitinsuchamannerthatitsmirrorimageisnonsuperimposable.反1,3二氟反2,4二氯环丁烷第28页Chirality and Symmetry判断分子有没有手性方法：对称面:非手性对称中心:非手性Carbon-basedStereogenicCenters:Themostprevalentstereogeniccentersinorganicchemistryarecarbonatoms,whichhavefourdifferentgroupsboundtothem.第29页第30页DiastereomersarestereoisomersthatarenotenantiomersIsomerswithmorethanonechiralcarbon:amaximumof2nstereoisomerscanbeobtained第31页IdentificationofAsymmetricCarbonsinCyclicCompoundsthesetwogroupsaredifferentcis-1-bromo-3-methylcyclohexanetrans-1-bromo-3-methylcyclohexane第32页MesoCompoundsHavetwoormoreasymmetriccarbonsandaplaneofsymmetryTheyareachiralmolecules第33页第34页Aslongasanyoneconformerofacompoundhasaplaneofsymmetry,thecompoundwillbeachiralplaneofsymmetryplaneofsymmetry第35页7.4 Properties of Chiral Molecules:Optical Activity7.4.1 Plane-polarized light 偏振光l光波：光波：电磁波，电场或磁场沿光波前进垂直方向振。电磁波，电场或磁场沿光波前进垂直方向振。l电场振动平面与磁场振动平面垂直电场振动平面与磁场振动平面垂直。第36页Nicol prisms:Plane-polarized light 偏振光:经过棱镜后光线电场或磁场只在一个平面上振动第37页7.4.2 Optical Activity 旋光性Asubstancewhichdoesnotcauserotationoftheplaneofpolarizedlightissaidtobeoptically inactive.第38页lAsubstancewhichcausestheplaneofpolarizedlighttoundergoarotationissaidtobeopticalactive.lTheangleofrotationissimplereferredtoasobservedrotation(旋光度).ChenliChenli陈立陈立第39页Thephysicalpropertiesofenantiomersareidentical(m.p.,b.p.,n,d,m,etc.)exceptthedirectioninwhichtheyrotateplanepolarizedlight.Enantiomersareopticalisomers.samplepolarizerplane-polarizeddextrorotatory(d)or(+)levorotatory(l)or()opticallyinactiveopticallyactive第40页第41页Chiralcompoundsareopticallyactive;theyrotatetheplaneofpolarizedlight.Clockwise(+)Counterclockwise(-)DifferentfromR,SconfigurationAchiralcompoundsdonotrotatetheplaneofpolarizedlight.Theyareopticallyinactive.第42页lMeasuringOpticalActivity:Opticalactivityistheabilityofachiralmoleculetorotatetheplaneofplane-polarizedlight.Itismeasuredusingapolarimeter,whichconsistsofalightsource,polarisinglens,sampletubeandanalyzinglens.lRotationoftheplaneofpolarizedlightintheclockwisesenseistakenaspositive(+),whilerotationinanticlockwisesenseistakenasanegative(-).lTheclassictermsforpositiveandnegativerotationsaredextrorotatory(右旋)(d)(+)andlevorotatory(左旋)(l)(-).第43页lWhenrotationisquantifiedusingapolarimeteritisknownasanobservedrotation,becauserotationisaffectedbypathlength(l,thetimethelighttravelsthroughasample)andconcentration(c,howmuchofthesampleispresentthatwillrotatethelight).lWhentheseeffectsareeliminatedastandardforcomparisonofallmoleculesisobtained,thespecificrotation(比旋光度比旋光度),a a.a a=100a/cllwhenconcentrationisexpressedasgsample/100mlsolution第44页ApolarizermeasuresthedegreeofopticalrotationofacompoundTheobservedrotation()TisthetempinCisthewavelengthisthemeasuredrotationindegreeslisthepathlengthindecimeterscistheconcentrationingramspermLEachopticallyactivecompoundhasacharacteristicspecificrotation比旋光度比旋光度第45页OpticallyPureIfonlyoneenantiomerispresentasampleisconsideredtobeopticallypure.Whenasampleconsistsofamixtureofenantiomers,theeffectofeachenantiomercancelsout,moleculeformolecule.DeterminingOpticalPurity:Theopticalpurityortheenantiomericexcess(ee%)ofasamplecanbedeterminedasfollows:Opticalpurity=%enantiomericexcess=%enantiomer1-%enantiomer2=100amixture/apuresampleee%=100(R-S)/(R+S)whereR=concentrationoftheR-isomerS=concentrationoftheS-isomer第46页Aracemic(外消旋)mixture,whichcontainsanequalamountofthetwoenantiomers,isopticallyinactiveopticalpurity=observedspecificrotationspecificrotationofthepureenantiomerenantiomericexcess=excessofasingleenantiomerentiremixture第47页Polarimeter旋光仪测定液体或溶液旋光程度仪器工作原理:第48页Theclassictermsforpositiveandnegativerotationsaredextrorotatory(右旋)(d )(+)andlevorotatory(左旋)(l)(-).比旋光度表示：葡萄糖（水溶液）(Glucose)(20C,钠光灯)陈立陈立=+52.5(H2O)20D第49页Enantiomers(对映(结构)体)willrotatetheplaneofpolarisationinexactlyequalamounts(samemagnitude)butinoppositedirections.Dextrorotarydesignatedas(+),clockwiserotation(totheright)Levorotarydesignatedas(-),anti-clockwiserotation(totheleft)第50页7.4.3 Chirality and Optical Activity手性只能在手性环境中识别手性只能在手性环境中识别 在非手性环境中（除了旋光性），对映体物在非手性环境中（除了旋光性），对映体物理，化学性质相同理，化学性质相同识别手性惯用伎俩是测定旋光性识别手性惯用伎俩是测定旋光性手性化合物在液态或溶液中是旋光手性化合物在液态或溶液中是旋光有些非手性化合物在液晶状态下有旋光性有些非手性化合物在液晶状态下有旋光性旋光方向与构型没有对应关系旋光方向与构型没有对应关系外消旋体外消旋体 (Racemic modification):由等量对映体组成无旋光性物质由等量对映体组成无旋光性物质ChenliChenli第51页7.5 Absolute and Relative ConfigurationlAbsoluteConfiguration绝对构型Whentheprecisearrangementofsubstituentsatastereogeniccentreisknowntheabsoluteconfigurationofthemoleculeisknown.Thisisusuallyaccomplishedbysolvingthex-raycrystalstructureofamolecule,amethodthatisnotalwaysreadilyavailable.l按要求构型式表示立体异构体与其真正构型相同构型式第52页Relative Configuration相对构型Thearrangementofatomsinanopticallyactivemolecule,basedonchemicalinterconversionfromortoaknowncompound,isarelativeconfiguration.Relative,becausethereisnowayofknowingjustbylookingatastructurewhethertheassignmentof(+)or(-)iscorrelated相关toaparticularisomer,RorS.IfthenameofacompoundincludesboththesignofrotationandthedesignationRorSthentheabsoluteconfigurationofthatcompoundisknown.第53页Reactionsofcompoundsthatcontainanasymmetriccarbon.Noreactionattheasymmetriccarbon;boththereagentandtheproducthavethesamerelativeconfiguration.Ifareactionbreaksabondattheasymmetriccarbon,youneedtoknowthereactionmechanisminordertopredicttherelativeconfigurationoftheproduct.第54页RelativeConfiguration1906,RosanoffAM选定D-(+)-glyceraldehydeL-(-)-glyceraldehyden.化甘油醛Isotopes:HvsD?StilluseatomicnumbersoDHSameatomattached?Bymovingoutoneunitatatime,locatethefirstpointofdifferenceandapplyrulesthere.第55页关联构型：在不包括与手性碳连接四个键断裂前提下D型:由D-(+)-甘油醛反应取得或可转变为D-(+)-甘油醛化合物构型。L型:由L-(-)-甘油醛反应取得或可转变为L-(-)-甘油醛化合物构型相对构型：因为直接或间接与甘油醛关联手性化合物构型。第56页实例：实例：1951,BijvoetJM确定(+)酒石酸绝对构型，从而推断出(+)甘油醛构型与Rosanoff假设型相同。结论：l（）甘油醛相对构型即为绝对构型；l全部与（）甘油醛关联得出构型也都是绝对构型第57页7.6 The Cahn一Ingold-Prelog R-S Notational SystemTheCahn-Ingold-PrelogR/Srulesareusedfornamingenantiomers.1.AssignprioritiestothefourgroupsaccordingtotheSequenceRules.2.Orientthemoleculesothatthelowestprioritygrouppointsawayfromyou.3.Determinethedirectionofprocessionoftheotherthreegroups,fromhighesttolowest:Ifthisisclockwise,thenthecenterisR(Latin:rectus=right)clockwise=R(rectus)Ifthisiscounterclockwise,thenitisS(Latin:sinister=left)counterclockwise=S(sinister)第59页NamingEnantiomersRankthegroups(atoms)bondedtothechiralitycenterTheR,Ssystemofnomenclature第60页R/S命名法命名法:Clockwise:Anticlockwise:RectusSinister左侧(R)-lacticacid(S)-lacticacidIf the name of a compound includes both the sign of rotation and the designation R or S then the absolute configuration of that compound is known.第61页Absoluteconfigurations:RandS(R)-2-butanol(S)-2-butanol第62页Designatetheconfigurationofatomsatastereocenter.Wecandesignatewhichiswhichbyassigninganabsoluteconfigurationtoeachofthese(RorS)byasetofrules,butwhichis(+)andwhichis()?Thereisnorelationshipbetweenamoleculesabsoluteconfigurationanditsopticalrotation(itsrelativeconfiguration).()(+)Answer:but,第63页Namethefollowingcompounds,includingRorSdesignation.第64页Namethefollowingcompounds,includingRorSdesignation.(S)-1-bromo-2-methylbutane12341234(R)-3-methylcyclohexene第65页7.7 Fischer Projection Formulas7.7.1 Projection Formulas 投影式 要求：横向棱边：指向观察者，用虚线表示垂直棱边：背向观察者，用实线表示第66页等同于：第67页lThevertical(垂直)bondsatthestereogeniccenteraredirectedawayfromyou.lThehorizontalbondspointstowardyou.注：习惯上，含碳基团置于竖键方向；命名时编号最小碳原子置于上端7.7.2 Fischer Projection Formulas第68页DeterminingRandSinFischerprojections:(R)-2-butanol-whenlowestprioritygroupisonaverticalbond(back):readnormally(S)-2-butanol-whenlowestprioritygroupisonahorizontalbond(forward):readbackward第69页FischerProjection能够在纸面上旋转902n构型保持在纸面上旋转90(2n+1)构型翻转第70页lFischer投影式不可离开纸面翻转lFischer投影式中任意三个基团可同时在不改变彼此相对位置下沿闭合环移动第71页ManipulatingFischerprojections:第72页实例:第73页AssignRandSconfigurations.Thendeterminewhetherthestructuresineachofthefollowingpairsareenantiomersoridentical.Check Answer第74页Answer:AssignRandSconfigurations.Thendeterminewhetherthestructuresineachofthefollowingpairsareenantiomersoridentical.12434231SSidentical RSenantiomers31214234SRenantiomersSRenantiomers第75页LouisPasteuronlyproductsoriginatingundertheinfluenceoflifeareasymmetric,becausethecosmici.e.generative,lifeforcesthatpresideovertheirformationarethemselvesasymmetric.Asymmetrydifferentiatestheorganicworldandthemineralworld.Spontaneousgenerationisachimera“Germtheory(annihilatingthespontaneousgenerationtheory)foundationofallmicrobiologicaltechniques第76页7.8 Physical Properties of Enantiomers第77页第78页7.9 Stereochemistry in Chemical Reactions That Produce Chiral Molecules7.9.1 Reactions that create a chiral centerRule:Opticallyinactivestartingmaterialcangiveonlyopticallyinactiveproducts第79页StereochemistryofElectrophilicAdditionReactionsofAlkenesWhatistheabsoluteconfigurationoftheproduct?第80页Additionreactionsthatformoneasymmetriccarbon第81页sp2,planar50/50Mixture第82页Reactions that create a chiral center第84页Drawtheproductsofthefollowingreactions,showingstereochemistrywhererelevant.第85页Drawtheproductsofthefollowingreactions,showingstereochemistrywhererelevant.第86页7.10 Chiral Molecules with Two or More Stereogenic Centers7.10.1 Diastereomers and EnantiomersDiastereomers:stereoisomersthatarenotmirrorimagese.g.eclipsedandstaggeredantiandgauchecisandtransconformationaldiastereomersconfigurationaldiastereomersDiastereomershavedifferentphysicalproperties(i.e.,canbeseparated).nchiralcarbons2npossiblestereoisomers第87页e.g.22=4possiblestereoisomersenantiomersenantiomersdiastereomers第88页Drawallstereoisomersof2-bromo-3-chloropentane.IndicateRandSconfigurationsofeachstereogeniccenter.Givetherelationshipsbetweeneachpairofstereoisomers.Check Answer第89页Besystematic.Drawonestereoisomer.Thendrawitsmirrorimage.Thenchangeonechiralcenteranddrawitsmirrorimage.SRSRSRRSEnantiomers:IandII;IIIandIVDiastereomers:IandIII;IandIV,IIandIII;IIandIV第90页7.10.2 Diastereomers:pairs of enantiomerserythrodiastereomerthreodiastereomerErythro(赤赤式)Threo (苏式)第91页PerspectiveformulaFischerprojection第92页3chiralcarbons23=8possiblestereoisomersR,R,R:S,S,SR,R,S:S,S,RR,S,R:S,R,SS,R,R:R,S,Senantiomersdiastereomers第93页Drawallstereoisomersof2,3-dibromohexane.IndicateRandSconfigurationsofeachstereogeniccenter.Givetherelationshipsbetweeneachpairofstereoisomers.Check Answer第94页SinceIIIhasaplaneofsymmetry,soismeso,thereareonlythreestereoisomers.(ThemirrorimageofIIIwouldnotanenantiomer,butwouldbeidenticaltoIII.)RSSSRREnantiomers:IandIIDiastereomers:IandIII;IIandIIIplaneofsymmetry;meso第95页7.10.4 Stereoisomers in substituted cycloalkanessachiral(planeofsymmetry)but:chiral,enantiomers第96页cis-Cyclopropane-1,3-dicarboxylic acidCyclopropane第97页第98页Stereoisomersinsubstitutedcyclohexanes第99页1第100页Indicatewhethereachofthefollowingcyclicstructureswouldbechiralorachiral.Ifacompoundischiral,givetheRorSconfiguration.Ifacompoundisachiral,explainwhy.Check Answer第101页Lookforstereogeniccarbonsandplanesofsymmetry.Rememberthataplaneofsymmetrycandissectanatomorabond.achiral:mesochiralachiral:nostereogeniccarbonachiral:mesoachiral:mesoRRRRRSSS第102页第103页Determinewhethereachofthefollowingpairsofstructuresrepresentidenticalcompounds,enantiomers,ordiastereomers.第104页Determinewhethereachofthefollowingpairsofstructuresrepresentidenticalcompounds,enantiomers,ordiastereomers.enantiomersdiastereomersenantiomersenantiomersdiastereomersenantiomers第105页7.13 Chemical Reactions That Produce Diastereomersbutstereospecificreaction:differentstereoisomericstartingmaterialsgivedifferentstereoiosmericproductsracemicmixtureracemicmixturediastereomers第106页racemicmeso第107页68%32%opticallyactiveGenerationofanewchiralcenterinachiralmoleculedoesnotnecessarilyproduceequalamountsofthetwodiastereomers.第108页Drawtheproductsofthefollowingreactions,showingallstereoisomers.Ifmorethanonestereoisomerisformed,givetherelationship.Check Answer第109页Theproductsareshownhere.Therelationshipbetweenthestereoisomersisgiven.enantiomersmesodiastereomersachiral(nochiralcenter)第110页III.ResolutionofEnantiomersseparationofthetwoenantiomersEnantiomers:identicalphysicalproperties;cantbeseparatedDiastereomers:differentm.p.,b.p.,solubility,etc.-canbeseparatedbydistillation,recrystallization,chromatography,etc.Scheme:diastereomers第111页(+)-lacticacid(-)-lacticacidLacticacid乳酸透视式(PerspectiveFormulas)=+2.6-2.6(H2O)陈立陈立第112页7.14 Resolution of EnantiomersResolutionofEnantiomersseparationofthetwoenantiomersEnantiomers:identicalphysicalproperties;cantbeseparatedDiastereomers:differentm.p.,b.p.,solubility,etc.-canbeseparatedbydistillation,recrystallization,chromatography,etc.Scheme:diastereomers第113页RacemicMixtureTartaricacid酒石酸:opticallyactiveRacemicacid:notopticallyactivePasteur:Racemic=L-tartaric+D-tartaric第114页Example:第115页ResolutionofRacemicMixtures+Racemicmixtureofritalinicacid(R,R)and(S,S)(S)1-Phenylethylamine(R,R)ritalinate(S)-1-Phenylethylamoniu