天津大學有機化學雙語PPT有機化學部分Chapter 7

Chapter7Stereochemistry,7.1MolecularChiralityandEnantiomers7.1.1MolecularChiralityandEnantiomersCharacteristicofenantiomersChiralmoleculesChirality7.1.2MolecularSymmetryandAsymmetricMoleculesSymmetricelementsAchiralMolecules7.1.3PropertiesofChiralMolecules:OpticalActivity7.1.4RepresentationandNomenclatureofChiralMolecules,A.RepresentationFischerprojectionsB.NamingenantiomerswithonestereocenterbyR-Snotationalsystem7.2ChiralMoleculesWithTwoStereocenters7.2.1ChiralMoleculesWithTwoDifferentStereocenterDiastereomers7.2.2StereoisomersWithTwoSameStereocentersMeso-form7.2.3ResolutionofEnantiomers,Cis-,Trans,Molecularstructure,Molecularconstitution,Constitutionalisomers:tohavethesameMolecularformula.,Molecularconfiguration（構(gòu)型）,Stereoisomers:,Thesamemole.constitution,Thedifferentspatialarrangementofatomsorgroups,Enantiomers(對映異構(gòu)體),Diastereomers(非對映異構(gòu)體),Theformerisunchang-edbyrota-tionofC-CSinglebond,Configurationalisomers,?,Molecularconfor-mation(構(gòu)象),Conformers:,Thesameconfiguration,ThedifferentspatialarrangementofatomsorgroupsbyrotationofC-Csinglebond,Theatomsarebondedindifferentorder:Cskeletonisomers;isomersofthefunctionalgroupsite;isomersoffunctionalgroup:Ex.CH3CH2OH,CH3OCH3,7.1MolecularChirality手(征)性andEnantiomers,7.1.1MolecularChiralityandEnantiomers,P183,AtetrahedronCisbondedtofourdifferentgroups,itsnotsuperposableonitsmirrorimage,Ex.Bromochlorofluoromethane:,Enantiomers,Characteristicofenantiomers,Thesamemole.constitution.2.Therelationshipofenantiomers:,objectandmirrorimage,3.Nonsuperposable,4.Thesamephysicalproperties,thesimilarchemicalproperties.,Chiralmolecules:,withitsenantiomer,Chirality:,Mole.isntsuperposablewiththeirmirrorimage,Stereocenterorstereogeniccenter,asymmetriccenter.,*,1,2-Epoxypropane(1,2-環(huán)氧丙烷),Limonene(檸檬油精),*,Themoleculethatcontainsonechiralcenterhaveapairofenantiomers,Anisotope,Chiralcenter:thecarbonwith4differentgroups.Ex.2-butanol:C2,(-)-Lacticacid(乳酸),Achiralcenter:aCatomisattachedby2ormoresamegroups.,Achiralmolecule(非手性分子).,Themoleculeisachiralandissuperposablewithitsmirrorimage.,7.1.2MolecularSymmetryandAsymmetricMolecules,Symmetricelements:,A.Aplaneofsymmetry(對稱面)(),Aplanebisectsamoleculesothatonehalfofmoleculeisthemirrorimageoftheotherhalf.,P185,6.2,Ex.2-Chloropropane,2.Allatomesinamoleculeareonaplane.,Ex.(E)-1,2-Dichloroethene,b.Centerofsymmetry(i),Ifanystraightlinepassesaatomandmolecularcenter,thesameatomorgroupisencounteredonthesiteatequaldistancebutintheoppositedirection.,Ex.trans-2,4-dichloro-1,3-difluorocyclo-butane,Anymoleculewithaplaneofsymmetryoracenterofsymmetry-Achiralmolecule,Asymmetricmolecule.,Anychiralmoleculeisasymmetricone.,Nonsuperposablewithitsmirrorimageandhaveaenantiomer.,7.1.3PropertiesofChiralMolecules:OpticalActivity(旋光活性or光學活性),Opticalactivity:,Whenabeamofplane-polarizedlight(平面偏振光)passthroughanenatiomer,theplanarpolarizationrotates.,Separateenantiomersrotatetheplaneofplane-polarizedlightequalamountsandinoppositedirection.,Opticallycompounds,OneenatiomerLevo-(左旋-)anticlockwise(-),OtherenantiomerDextro-(右旋)clockwise(+),(-)-2-Butanol,(+)-2-Butanol,ThemixturesthatcontainequalamountsofenantiomersareRacemic(外消旋).,()-2-Butanol,Polarimeter(旋光儀):,Tomeasuretheeffectofplane-polarizedlightonopticallyactivecompounds,LightsourcePolarizerSampletubeAnalyzer(起偏器)(檢偏器),Specificrotation(比旋光度),:Theobservedrotation,c:Theconcentrationofthesample(g/mL)l:Thelengthofthesampletube(dm):wavelength(D,589nm)Na,(-)-2-Butanol,(+)-2-Butanol,D=-13.25,D=+13.25,Opticalpurity(光學純度):,Percentenantiomericexcess(對映體過量百分數(shù)),Ex.Specificrotation:+6.76,50%pure(+)-2-butanol+50%()-2-butanol,JeanBaptisteBiotFrenchPhysicistb.1774d.1862,JeanBaptisteBiotwasborninParis,France,andwaseducatedthereatthecolepoly-technique.Hisworkondeterminingtheopticalrotationofnaturallyoccuringmoleculesincludedanexperimentonturpentine.,7.1.4RepresentationandNomenclatureofChiralMolecules,A.Representation:,1.Wedgeanddashdrawing(傘式):,(+)-2-Butanol,2.Fischerprojections,Ch.P113(二),Representationby,Thelongestcarbonchainisonverticalposition.Thelowestnumberedcarbonisatthetop.,Therulefordrawing:,Theintersectionofverticalandhorizontallines:chiralCatom.,Ex.,(-)-2-Butanol,Verticallinerepresentsthebondthatprojectbehindtheplaneofthepaper;Horizontallinerepresentsthebondthatprojectoutoftheplaneofthepaper.,(南)P178,HermannEmilFischerGermanyBerlinUniversityBerlin,Germanyb.1852d.1919,Generallyconsideredthegreatestorganicchemistofhistime,Fischerreceivedthe1902NobelPrizeinChemistryforhisworkoncarbohydratesandpurines.Hisdiscoverythatphenylhydrazinereactswithcarbohydratestoformosazonesenabledhimtoelucidatethestereochemistryofsugars.Firsttosynthesizeadenineandguanine,hemadethefirstsyntheticnucleotides.Amongmanyothercontributionswashisworkonproteinstructureandsynthesis,thelock-and-keymodelforenzymereactions,structureoftriarylmethanedyes,andthedesignoflaboratoryhoodsandsafetyequipment.,CharacteristicsofFischerprojection,Onegroupisfixed,theotherthreegroupsarerotatedinturn,theconfigurationisnotchanged.,Torotatetheprojectionto90,ontheplaneofthepaper,theotherenatiomerwasgot:,(+)-2-Bromobutane,(-)-2-Bromobutane,(-)-,Toexchangeanytwogroups,theconfigurationwaschanged,theotherenantiomerwasgot.,(-)-2-Bromobutane,(+)-,(+)-,(-)-,(+)-,(+)-,B.NamingenantiomerswithonestereocenterbyR-Snotationalsystem,P193,6.6,Designationofabsoluteconfiguration,RankthesubstituentsaccordingtoCahn-Ingold-Prelogrule(序列規(guī)則).,2.Orientthemoleculesothatthelowestrankedsubstituentpointsawayfromyou.,(-)-2-Butanol,3.Drawthetreehighestrankedsubstituentfromthehighestonetolowestone.,Thedirection:,Clockwise:(R)-,Anticlockwise:(S)-,(R)-2-Butanol,7.2ChiralMoleculesWithTwoStereocenter,7.2.1ChiralMoleculesWithTwoDifferentStereocenter,Thefourstereoisomersof2,3-dihydroxybutanoicacid,P194,(-)-Lacticacid,P196,6.7,(R)-甘油醛,(S)-甘油醛,(1)(2)(3)(4),(2R,3R)-,(2S,3S)-,(2R,3S)-,(2S,3R)-,2,3-Dihydroxybutanoicacid(2,3-二羥基丁酸),Normallynstereocenters2nstereoisomers,Relationshipsofstereoisomers:,Enantiomers:,Diastereomers:(非對映異構(gòu)體),(1),(3),(4),(2),Therelationshipbetweendiastereomersisnotrelatedasanobjectanditsmirrorimige.,Nomenclaturefordiastereomers:,BaseonFischerprojection:,ThesamegroupsareonthesamesidesofCchain:erythro-(赤蘚式)-,ThesamegroupsareontheoppositesidesofCchain:threo-(蘇蘚式)-,erythro-(赤型)-,(2R,3R)-,threo-(蘇型)-,(2S,3R)-,7.2.2StereoisomersWithTwoSameStereocenters,Ex.Tartaricacid(酒石酸),(2R,3R)-,(2S,3S)-,(2R,3S)-,(5)(6)(7)(8),erythro-,mesoform(內(nèi)消旋體),ThemesoformisachiralMole.,7.2.3ResolutionofEnantiomers（對映體的拆分）,Pasteur:,Sodiumammoniumtartrate(酒石酸銨鈉),Recrystallization(重結(jié)晶),Twokindcrystalsaremirrorimage,LouisPasteur1822-1895,ThescientificcontributionsofPasteurwereamongthemostvaluableinthehistoryofscience,andheisclaimedequallybychemistryandmicrobiology.Bestknowntochemistsforhisworkonthetartaricacids,herecognizedthestructuralrelationships(nowcalledchirality)responsibleforopticalisomerism,andthatmicroorganismscandistinguishbetweenenantiomers.Pasteuralsoshowedthatmicro-organismscausefermentationandvariousdiseases,andhedevelopedmethodsforpasteurizationandforvaccinationagainstanthraxandrabies.Hisworksavedthewine,beer,andsilkwormindustriesforFrance.,Resolutionofracemiclacticacid,6.25(a),(d)6.266.306.33(a)(c),ProblemstoChapter6,P212,6.346.