提示：系统监测到该条供求信息的发

97,Chapter17:AldehydesandKetones:NucleophilicAdditiontotheCarbonylGroup17.1:Nomenclature(pleaseread)17.2:StructureandBonding:Carbonylgroupshaveasignificantdipolemoment,Aldehyde2.72DKetone2.88Carboxylicacid1.74Acidchloride2.72Ester1.72Amide3.76Nitrile3.90Water1.85,Carbonylcarbonsareelectrophilicsitesandcanbeattackedbynucleophiles.Thecarbonyloxygenisabasicsite.,喷灌机,98,17.3:PhysicalProperties(pleaseread)17.4:SourcesofAldehydesandKetones(Table17.1,p.708)1a.Oxidationof1and2alcohols(15.10)1b.Fromcarboxylicacids1c.Ketonesfromaldehydes,99,Ozonolysisofalkenes(6.20)Hydrationofalkynes(9.12)Friedel-CraftAcylation(12.7)-arylketones5.Hydroformylationofalkenes(pleaseread),100,17.5:ReactionsofAldehydesandKetones:AReviewandaPreview,Reactionsofaldehydesandketones:Review:Reductiontohydrocarbonsa.Clemmensonreduction(Zn-Hg,HCl)b.Wolff-Kishner(H2NNH2,KOH,),101,Reductionto1and2alcohols(15.2)3.AdditionofGrignardReagents(14.6-14.7),102,17.6:PrinciplesofNucleophilicAddition:HydrationofAldehydesandKetonesWatercanreversiblyaddtothecarbonylcarbonofaldehydesandketonestogive1,1-diols(geminalorgem-diols),R=H,H99.9%hydrateR=CH3,H50%R=(H3C)3C,H17%R=CH3,CH30.14%R=CF3,CF399%,ThehydrationreactionisbaseandacidcatalyzedBase-catalyzedmechanism(Fig.17.1):hydroxideisabetternucleophilethanwater,103,Acid-catalyzedmechanism(Fig.17.2):protonatedcarbonylisabetterelectrophile,Doesaddingacidorbasechangetheamountofhydrate?DoesacatalystsaffectGo,G,both,orneither,Thehydrationisreversible,104,17.7:CyanohydrinFormationAdditionofH-CNaddstothealdehydesandunhinderedketones.(relatedtothehydrationreaction)TheequilibriumfavorscyanohydrinformationMechanismofcyanohydronfromation(Fig.17.3),105,17.8:AcetalFormationAcetalsaregeminaldiethers-structurallyrelatedtohydrates,whicharegeminaldiols.,hydrate(gem-diol),aldehyde,hemi-acetal,acetal(gem-diether),ketone,hemi-ketal,ketal(gem-diether),106,Mechanismofacetal(ketal)formationisacid-catalyzed(Fig17.4),Themechanismforacetal/ketalformationisreversibleHowisthedirectionofthereactioncontrolled?,Dean-StarkTrap,107,Dioxolanesanddioxanes:cyclicacetal(ketals)from1,2-and1,3-diols,1,3-dioxolane,1,3-dioxane,1,2-diol,1,3-diol,108,17.9:Acetals(Ketals)asProtectingGroupsProtectinggroup:Temporarilyconvertafunctionalgroupthatisincompatiblewithasetofreactionconditionsintoanewfunctionalgroup(withtheprotectinggroup)thatiscompatiblewiththereaction.Theprotectinggroupisthenremovedgivingtheoriginalfunctionalgroup(deprotection).,109,Thereactioncannotbedonedirectly,asshown.Why?,Aldehydeorketone,hemi-acetalorhemi-ketal,acetalorketal,17.10:ReactionwithPrimaryAmines:Imines(Schiffbase),Aldehydeorketone,carbinolamine,imine,110,Mechanismofimineformation(Fig.17.5):,SeeTable17.4fortherelatedcarbonylderivative,oximes,hydrazoneandsemicarbazides(pleaseread),111,17.11:ReactionwithSecondaryAmines:Enamines,1amine:2amine:,ImineIminiumion,iminiumionenamine,ketonewith-protons,Mechanismofenamineformation(Fig17.6),112,17.12:TheWittigReaction1979NobelPrizeinChemistry:GeorgWittig(WittigReaction)andH.C.Brown(Hydroboration)Thesynthesisofanalkenefromthereactionofanaldehydeorketoneandaphosphorusylide(Wittigreagent),adipolarintermediatewithformaloppositechargesonadjacentatoms(overallchargeneutral).,aldehydeorketone,triphenylphosphoniumylide(Wittigreagent),alkene,triphenylphosphineoxide,Acceptedmechanism(Fig.17.7)(pleaseread),113,TheWittigreactiongivesC=Cinadefinedlocation,basedonthelocationofthecarbonylgroup(C=O)TheWittigreactionishighlyselectiveforketonesandaldehydes;esters,lactones,nitrilesandamideswillnotreactbutaretoleratedinthesubstrate.Acidicgroups(alcohols,amineandcarboxylicacids)arenottolerated.Predictingthegeometry(E/Z)ofthealkeneproductiscomplexandisdependentuponthenatureoftheylide.,114,17.13:PlanninganAlkeneSynthesisviatheWittigReaction,AWittigreagentispreparedfromthereactionofanalkylhalidewithtriphenylphosphine(Ph3P:)togiveaphosphoniumsalt.Theprotonsonthecarbonadjacenttophosphorousareacidic.,Deprotonationofthephosphoniumsaltwithastrongbasegivestheylide.Aphosphoraneisaneutralresonancestructureoftheylide.,115,TherewillbetwopossibleWittigroutestoanalkene.Analyzethestructureretrosynthetically,i.e.,workthesynthesisoutbackworksDisconnect(breakthebondofthetargetthatcanbeformedbyaknownreaction)thedoublybondedcarbons.Onebecomesthealdehydeorketone,theothertheylide,116,17.14:StereoselectiveAdditiontoCarbonylGroups(pleaseread)17.15:OxidationofAldehydes,Increasingoxidationstate,117,AldehydesareoxidizedbyCr(VI)reagentstocarboxylicacidsinaqueousacid.Thereactionsproceedsthroughthehydrate,118,17.16:Baeyer-VilligerOxidationofKetones.Oxidationofketoneswithaperoxyacid(mCPBA)togiveasesters,Oxygeninsertionoccursbetweencarbonylcarbonandmorethesubstituteda-carbon,119,19.17:SpectroscopicAnalysisofAldehydesandKetonesInfraredSpectroscopy:highlydiagnosticforcarbonylgroupsCarbonylshaveastrongC=Oabsorptionpeakbetween1660-1770cm1AldehydesalsohavetwocharacteristicCHabsorptionsaround2720-2820cm1,Butanal2-Butanone,C=O(1730cm-1),C=O(1720cm-1),C-H,C-H,2720,2815cm-1,120,C=Ostretchesofaliphatic,conjugated,arylandcycliccarbonyls:,ConjugationmovestheC=Ostretchtolowerenergy(right,lowercm-1)Ring(angle)strainmovestheC=Ostretchtohigherenergy(left,highercm-1),121,1HNMRSpectraofAldehydesandKetones:The1Hchemicalshiftrangeforthealdehydeprotonis9-10ppmThealdehydeprotonwillcoupletotheprotonsonthe-carbonwithatypicalcouplingconstantofJ2HzAcarbonylwillslightlydeshieldtheprotonsonthe-carbon;typicalchemicalshiftrangeis2.0-2.5ppm,=9.8,t,J=1.8,1H,=1.65,sextet,J=7.0,2H,=2.4,dt,J=1.8,7.0,2H,=1.65,t,J=7.0,3H,122,=2.5(2H,q,J=7.3)2.1(3H,s)1.1(3H,t,J=7.3),7.0-6.0,2.7-1.0,=6.8(1H,dq,J=15,7.0)6.1(1H,d,J=15)2.6(2H,q,J=