参考成果第31讲

OrganicChemistry(Chapter15ReactionofJoelleWang(汪君)1FinalExaminationOrganicChemistryIJan.7th2014:9:00-11:00Room:306&Chapter10-Lecturenotes,homework,2Chapter15ReactionofOxidationofFormationofReductionofReactionofalcoholswithhydrohalicReactionofalcoholswithphosphorusDehydrationreactionofUniquereactionsofEsterificationofReactionsof3DehydrationReactionsofDehydrationReactionsofTodrivethisequilibriumtotheright,weremoveoneorbothoftheproductsastheyform,eitherbydistillingtheproductsoutofthereactionmixtureorbyaddingadehydratingagenttoremoveAlcoholdehydrationsgenerallytakeplacethroughtheE1isomerizationoftheproductsareso DehydrationReactionsofReviewtheutilityofdehydrationandgiveguidelinesforpredictingtheDehydrationusuallygoesbytheE1mechanism.Rearrangementsmayoccurtoformmorestablecarbocations.Dehydrationworksbestwithtertiaryalcoholsandalmostaswellwithsecondaryalcohols.Rearrangementsandpooryieldsarecommonwithprimaryalcohols.(Zaitsev'srule)Iftwoormorealkenesmightbeformedbydeprotonationofthecarbocation,themostsubstitutedalkeneusuallypredominates.Predicttheproductsofsulfuricacid-catalyzeddehydrationofthefollowing(a)1- (b)neopentyl6DehydrationReactionsofDehydrationReactionsofBimoleculardehydrationtoformethers(Industrial)双分子脱水成醚(工业上Insomecases,aprotonatedprimaryalcoholmaybeattackedbyanothermoleculeofthealcoholandundergoanSN2displacement.Bimoleculardehydrationcanbeusedtosynthesizesymmetricaldialkylethersfromsimple,unhinderedprimaryalcohols.Undertheacidicdehydrationconditions,tworeactionscompete:Elimination(togiveanalkene)competeswithsubstitution(togiveanether).8AnalcoholcanprotonateonthehydroxylgroupandlosewatertoformaAnalcoholcanprotonateonthehydroxylgroupandlosewatertoformacarbocation…DevelopamechanismtoaccountforthefollowingProtonatingthedoublebondwouldformthetertiarycarbocation,activatingthewrongendofthedoublebond.Also,thereisnogoodnucleophilicsiteonthesidechaintoattackthiscarbocationtoformthecorrectring.Protonatingthedoublebondisadeadend.UniquereactionsofThePinacolRearrangementFormallyaAcid-catalyzed:thefirststepisprotonationofofthehydroxyloxygens.Lossofwatergivesatertiarycarbocation,asexpectedforanytertiaryMigrationofamethylgroupplacesthepositivechargeonthecarbonatombearingthesecond-OHgroup,whereoxygen'snonbondingelectronshelptostabilizethepositivechargethroughresonance.Thisextrastabilityisthedrivingforcefortherearrangement,whichconvertsarelativelystable3ocarbocationintoanevenbetterresonance-stabilizedcarbocation.Deprotonationoftheresonance-stabilizedcationgivestheproduct,共振-稳定的碳正离子去质子化得到产物—频哪醇 UniquereactionsofThePinacolRearrangementPage518Problem15-ProposeamechanismforeachUniquereactionsofPage519Problem15-Thefollowingreactioninvolvesastartingmaterialwithadoublebondandahydroxylgroup,yetitsmechanismresemblesapinacolrearrangement.Proposeamechanism,andpointoutthepartofyourmechanismthatresemblesapinacolrearrangement.UniquereactionsofPeriodicAcidCleavageofGlycols1,2-Diolssuchasthoseformedbyhydroxylationofalkenes,arecleavedbyperiodicTheproductsarethesameketonesandaldehydesthatwouldbeformedbyozonolysis-reductionofthealkene.Periodicacidcleavageofaglycolprobablyinvolvesacyclicperiodateintermediate：5EsterificationofEsternormallymeansanesterofacarboxylicacid:replacingthe-OHgroupofacarboxylicacidwiththe-ORgroupofanalcoholgivesacarboxylicester.Fischeresterification,showstherelationshipbetweenthealcoholandtheacidontheleftandtheesterandwaterontheright.Ifwemixisopropylalcoholwithaceticacidandaddadropofsulfuricacidasacatalyst,thefollowingequilibriumresults.drivingthereactiontotherightUsingalargeexcessofthealcoholortheacid.Addingadehydratingagentremoveswater(oneoftheproducts),加除水剂除 EsterificationofThereisamorepowerfulwaytoformanesterwithouthavingtodealwithanunfavorableequilibrium.Analcoholreactswithanacidchlorideinanexothermicreactiontogiveanester.EsterificationofAsulfateesterSulfateionsareexcellentleavinggroups.Nucleophilesreactwithsulfateesterstogivealkylatedproducts.的离去基团。亲核试剂与硫酸酯反应Nitrateestersareformedfromalcoholsandnitric高爆炸性物质：苦味酸，TNT三硝基甲苯)PETN高爆炸性物质：苦味酸，TNT三硝基甲苯)PETN季戊四醇四硝酸酯RDXdepartmentThebest-knownnitrateesteris“nitroglycerine,”whosesystematicnameisglycerylfromthereactionofglycerol(1,2,3-propanetriol)withthreemoleculesofnitricHighexplosive:picricacid,TNT(trinitrotoluene),PETN(pentaerythritoltetranitrate),andRDX(researchdepartmentexplosive).EsterificationofPhosphateEstersAlkylphosphatesarecomposedof1moleofphosphoricacidcombinedwith1,2,or3molesofanalcohol.Phosphateestersplayacentralroleinbiochemistry：phosphateesterlinkagescomposethebackboneofthenucleicacidsRNA(ribonucleicacid)andDNA(deoxyribonucleicacid).RNADNAReactionsofRemovethehydroxylprotonfromanalcoholbyreductionwithan"active"metalsuchassodiumorpotassium.Thisreactiongeneratesasodiumorpotassiumsaltofanalkoxideionandhydrogengas.Thereactivityofalcoholstowardsodiumandpotassiumdecreasesintheorder:methyl>1o>2o>3o.>Somealcoholsreactsluggishlywithbothsodiumandpotassium.Inthesecases,ausefulalternativeissodiumhydride,usuallyintetrahydrofuransolution.Thealkoxideionisastrongnucleophileaswellasapowerfulbase.Thealkoxideionreactswithprimaryalkylhalidesandtosylatestoformethers.烷氧基离子是强亲核试剂，可与伯卤代烷和对甲苯磺酸酯反应，形成醚 ReactionsofWilliamsonethersynthesis,isanSN2displacement:Thealkylhalide(ortosylate)mustbeprimarysothataback-sideattackisnothindered.Whenthealkylhalideisnotprimary,eliminationusuallyresults.ReactionsofWhyisthecyclohexylgroupchosenforthealkoxideandtheethylgroupchosenforhalide?Whynotusecyclohexylbromideandsodiumethoxidetomakecyclopentylethylether?GivethestructuresoftheintermediatesandproductsVthrough

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