第十一章醛和酮

第十一章醛和酮Aldehyde醛Ketone酮Carbonyl羰基1§1命名一、醛Rule:選主鏈,定母體；編號(hào)；排序甲醛methanalformaldehyde乙醛ethanalacetaldehyde4-甲基-2-乙基戊醛2-ethyl-4-methylpetanal烷－醛ane--alb-甲基戊醛或3-甲基戊醛b-methylpetanal23-甲基環(huán)己基甲醛3-methylcyclohexanecarbaldyhyde苯甲醛benzenecarbaldehyde

benzaldehydep-硝基苯甲醛p-nitrobenzenecarbaldehyde3-甲基-4-己烯醛3-methyl-4-hexenal3二、酮的命名Rule:選主鏈,定母體；編號(hào)；排序烷－酮ane--anone丙酮propanoneacetone

5-甲基-3-己酮5-methyl-3-hexanone

4-甲基環(huán)己酮4-methylcyclohexanone

1-苯基-1-丙酮1-phenyl-1-propanone

2,4-己二酮2,4-hexanedione

4-己烯-2-酮4-hexen-2-one4化合物普通命名法IUPAC命名法熔點(diǎn)/℃沸點(diǎn)/℃溶解度g/100gH2O甲醛HCHOformaldehydeformaldehyde-9221易溶乙醛CH3CHOacetaldehydeacetaldehyde-1212116丙醛CH3CH2CHOpropionaldehydepropanal-81497丁醛CH3(CH2)2CHOn-butyraldehydebutanal-9976微溶戊醛CH3(CH2)3CHOn-valeraldehydepentanal-92103微溶苯甲醛PhCHObenzaldehydebenzaldehyde-261780.3丙酮CH3COCH3acetonepropanone-9556∞丁酮CH3CH2COCH3ethylmethylketone2-butanone-8680262-戊酮CH3(CH2)2COCH3methylpropyl

ketone2-pentanone-781026.33-戊酮C2H5COC2H5dimethyl

ketone3-pentanone-401025環(huán)己酮cyclohexanonecyclohexanone-451552.4苯乙酮PhCOCH3methylphenylketone1-phenyl-1-ethanone21202不溶苯丙酮PhCOCH2CH3ethylphenylketone1-phenyl-1-propanone21218不溶二苯酮PhCOPhdiphenyl

ketoneDiphenyl

methanone48306不溶§2醛酮的物質(zhì)性質(zhì)5§3醛酮的化學(xué)性質(zhì)一、羰基的結(jié)構(gòu)與反應(yīng)特征sp2雜化，平面結(jié)構(gòu)sp3雜化，四面體親核加成反應(yīng)6二、羰基的親核加成反應(yīng)1.加HCNa-羥基酸a-氨基醇7Mechanism實(shí)驗(yàn)證據(jù)：加少量堿加速反應(yīng)的進(jìn)行相對活性：>>Problems:比較如下化合物與HCN反應(yīng)的活性大小>>芳環(huán)與羰基p-p共軛，減弱羰基碳正性8<叔丁基的立體位阻，妨礙親核試劑接近羰基碳(4)將如下化合物與HCN反應(yīng)的活性大小排序C>A>B>E>D脂肪族醛酮與HCN反應(yīng)活性，主要受空間因素影響(5)將如下化合物與HCN反應(yīng)的活性大小排序A>C>B芳香族醛酮與HCN反應(yīng)活性，主要受電子效應(yīng)的影響9反應(yīng)范圍RCHORCOCH38碳以下的環(huán)酮2.與飽和NaHSO3溶液反應(yīng)親核中心為S，不是O反應(yīng)范圍：RCHORCOCH38碳以下的環(huán)酮103.與ROH加成Mechanism半縮醛酸的作用活化羰基，增大羰基的碳正性縮醛11縮酮分水器縮醛縮醛(酮)的分解縮醛(酮)在堿性條件下是穩(wěn)定的，但對酸敏感12保護(hù)羰基134.與RSH（硫醇）加成硫代縮醛（酮）14Problem155.與H2O加成K平衡的大小取決于羰基上的取代基166.與金屬有機(jī)試劑RM加成RM:RMgBr,RLi,RC=CNa制備各種醇的方法RMgBr與RLi的區(qū)別177.與氨的衍生物加成反應(yīng)通式：1819活化羰基NH2失活羰基試劑水解20三、涉及羰基a-H的反應(yīng)1.a-H的酸性及烯醇平衡烯醇平衡212.a-鹵代及鹵仿反應(yīng)A.酸催化下的鹵代反應(yīng)動(dòng)力學(xué)實(shí)驗(yàn)：反應(yīng)速度與羰基化合物以及酸的濃度相關(guān)，但與鹵素的濃度無關(guān)結(jié)論：反應(yīng)的決速步驟在鹵素參與反應(yīng)之前22Mechanismfastslow酸催化烯醇化fastfast自動(dòng)催化反應(yīng)23B.堿催化下的鹵代反應(yīng)Mechanismfastslow24鹵仿碘仿反應(yīng)黃色25碘仿反應(yīng)的應(yīng)用鑒別有機(jī)分子中是否具有結(jié)構(gòu)單元反應(yīng)的方向酸性條件：鹵代反應(yīng)發(fā)生在取代基多的a碳上穩(wěn)定性<26堿性條件：鹵代反應(yīng)發(fā)生在取代基少的a碳上原因：決速步驟中堿奪取a-H形成烯醇負(fù)離子，取代少的a-C上H的酸性強(qiáng)，位阻小3.羥醛縮合(Aldol)反應(yīng)A.堿催化下的羥醛縮合反應(yīng)a,b-不飽和醛Mechanismslow27羥酮縮合B.酸催化下的羥醛縮合反應(yīng)28C.分子內(nèi)的羥醛縮合反應(yīng)D.交叉羥醛縮合反應(yīng)四種產(chǎn)物29交叉羥醛縮合反應(yīng)－a,b-不飽和醛酮的合成提供羰基提供a-H30不對稱的酮Aldol反應(yīng)的取向31四、氧化反應(yīng)1.強(qiáng)氧化劑：KMnO4/H+,K2Cr2O7/H+,HNO3322.弱氧化劑：Tollens試劑AgNO3/NH3.H2O[Ag(NH3)2]+OH-

Fehling試劑CuSO4/OH-+酒石酸鉀鈉333.拜爾－維立格氧化(Baeyer-Villiger)Mechanism反應(yīng)方向34R遷移能力：Ar>3o>2o>1o>CH3氫優(yōu)先遷移35五、還原反應(yīng)1.還原為醇A.催化氫化催化氫化活性：CHO>C=C>RCOR選擇性差36B.化學(xué)還原－LiAlH4,NaBH4選擇性好LiAlH4:可還原COR,CO2H,CN,NO2NaBH4:一般只能還原醛酮羰基37C.麥爾外因－彭多夫還原(Meerwein-Ponndorf)可逆Mechanism負(fù)氫轉(zhuǎn)移38歐芬腦氧化(Oppenauer)可逆Mechanism醇交換39D.金屬還原單分子還原：Na/C2H5OH;Fe/CH3CO2HMechanism負(fù)離子自由基40雙分子還原：Mg,Mg-Hg齊/非質(zhì)子性溶劑還原偶聯(lián)Mechanism412.還原為烴A.Clemmensen還原B.Wolff-Kischer還原黃鳴龍改進(jìn)42MechanismC.硫代縮酮的還原433.歧化反應(yīng)－Cannizzaro反應(yīng)無a-HMechanism負(fù)氫轉(zhuǎn)移親核加成44交叉歧化反應(yīng)四種反應(yīng)方式甲醛羰基活性高，優(yōu)先受到OH-的進(jìn)攻45六、其它重要反應(yīng)1.Wittig反應(yīng)Wittig試劑－磷葉立德(Yilde)A.Wittig試劑的制備46B.Wittig反應(yīng)的機(jī)理47C.Wittig反應(yīng)的應(yīng)用482.安息香縮合反應(yīng)Mechanism失去質(zhì)子決速步驟49原因：吸電子取代基減弱碳負(fù)離子的親核性給電子取代基減弱羰基碳的碳正性決速步反應(yīng)中提供碳負(fù)離子，親核性大反應(yīng)中提供羰基碳，其碳正性大503.貝克曼重排(Beckman)-反酮肟重排Mechanism特點(diǎn)：分子內(nèi)的反式重排手性碳構(gòu)型保持51七、羰基加成反應(yīng)的立體化學(xué)產(chǎn)生一個(gè)新的手性中心R,R’中不含手性碳，則得到外消旋體52Cram規(guī)則:不對稱醛酮與親核試劑加成時(shí)，親核試劑優(yōu)先從醛酮優(yōu)勢構(gòu)象中空間位阻較小的一邊，既較小基團(tuán)一邊進(jìn)攻羰基優(yōu)勢構(gòu)象：手性碳原子上最大基團(tuán)與羰基處于反式共平面時(shí)，其構(gòu)象最穩(wěn)定5354八、a,b-不飽和醛酮的反應(yīng)1.親核加成醛羰基活性高，傾向于1,2-加成；酮傾向于1,4-加成55A.與HCN加成B.與RMgX加成RMgX與加成a,b-不飽和醛酮作用，1,2-加成傾向大，但如羰基上有較大位阻取代基，則傾向于1,4-加成56C.與RLi加成RLi試劑活性高，傾向于1,2-加成D.與R2CuLi加成R2CuLi傾向于1,4-加成572.親電加成與HX加成，一般為1,4-加成Br2褪色58§4醛酮的制備一、醛的合成1.炔水合，胞二鹵代物水解592.芳烴氧化3.伯醇氧化604.Reimer-Tiemer反應(yīng)5.酰氯的部分還原A.Rosenmund還原61B.化學(xué)還原－LiAlH[(OC(CH3)3]36.酯與腈的部分還原62二、酮的制備1.甲基酮的合成RCOCH32.仲醇的氧化633.芳香酮的合成4.酰氯與有機(jī)銅化合物的反應(yīng)5.腈與有機(jī)鎂(鋰)的反應(yīng)6465KeyReactionsReactionwithGrignardReagentsTreatmentofformaldehydewithaGrignardreagentfollowedbyhydrolysisgivesaprimaryalcohol.Similartreatmentofanyotheraldehydegivesasecondaryalcohol.Treatmentofaketonegivesatertiaryalcohol.2.ReactionwithOrganolithiumReagentsReactionsofaldehydesandketoneswithorganolithiumreagentsaresimilartothosewithGrignarsreagents.3．ReactionswithAnionsofTerminalAlkynesTreatmentofanaldehydeorketonewiththealkalimetalsaltofaterminalalkynefollowedbyhydrolysisgivesana-alkynyalchol.4.ReactionwithHCNtoformCyanohydrins

Foraldehydesandmoststericallyunhinderedaliphaticketones,equilibriumfavorsformationofthecyanohydrin.Forarylketones,equilibriumfavorsstartingmaterials,andlittlecyanohydrinisobtained.665.TheWittigReaction

Treatmentofanaldehydeorketonewithatriphenylphosphonium

ylidegivesanoxaphosphetaneintermediate,whichfragmentstogivetriphenylphosphineoxideandanalkene.6.HydrationThedegreeofhydrationisgreaterforaldehydesthanforketones.7.AdditionofAlcoholstoFormHemiacetals

Hemiacetalsareonlyminorcomponentsofanequilibriummixtureofaldehydeorketoneandalcohol,exceptwherethe–OHandtheC=Oarepartsofthesamemoleculeandafive-orsix-memberedringcanform.8.AdditionofalcoholstoFormAcetals

Formationofacetalsiscatalyzedbyacid.Acetalsarestabletowaterandaqueousbasebutarehydrolyzedinaqueousacid.Acetalsarevaluableascarbonyl-protectinggroups.679.AdditionofSulfurNucleophiles:Formationof1,3-Dithianes

Themostcommonlyusedthiolforpreparationofthioacetalsis1,3-propanedithiol.Theproductiscalleda1,3-dithiane.10.AlkylationofAnionsDerivedfromAldehyde1,3-Dithianes

Treatmentofanaldehyde1,3-dithiane(pKa

31)withbutyllithiumgivesananion.Thisanioncanenterintosubstitutionreactionswithprimaryalkyl,allylic,andbenzylichalidesandadditionreactionswiththecarbonylgrouppfaldehydesandketones.11.AdditionofAmmoniaandItsDerivatives:FormationofImines

Additionofammoniaoraprimaryaminetothecarbonylgroupofanaldehydeorketoneformsatetrahedralcarbonyladditioncompound.Lossofwaterfromthisintermediategivesanimine.12.AdditionofSecondaryAmines:FormationofEnamines

AdditionofSecondaryaminetothecarbonylgroupofanaldehydeorketoneformsatetrahedralcarbonyladditionintermediate.Acid-catalyzeddehydrationofthisintermediategivesanenamine.6813.AdditionofHydrazineandItsDerivatives

Treatmentofanaldehydeorketonewithhydrazinegivesahydrazone.Derivativesofhydrazinereactsimilarly.14.Keto-Enol

Tautomerism

Theketoformpredominatesatequilibrium,exceptforthosealdehydesandketonesinwhichtheenolisstabilizedbyresonanceorhydrogenbonding.15.DeuteriumExchangeatthea-Carbon

Acid-orbase-catalyzeddeuteriumexchangeatana-carboninvolvesformationofanenolorenolateanionintermediate.16.Halogenationatthea-carbon

Therate-limitingstepinacid-catalyzeda-halogenationisformationofanenol.Inbase-promoteda-halogenation,itisformationofanenolateanion.6917.ThehaloformReactionThehaloformreactionoxidizesamethylketonetoacarboxylicacid.18.OxidationofanAldehydetoaCarboxylicAcid

Thealdehydegroupisamongthemosteasilyoxidizedfunctionalgroups.OxidizingagentsincludeKMnO4,K2Cr2O7,Tollens’reagent,H2O2,andO2.19.OxidationofaKetonetoanEster:TheBaeyer-VilligerRearrangementOxidationofaketonebyaperoxyacidinvolvesnucleaophilicadditiontothecarbonylgroupoftheketonetoformatetrahedralcarbonyladditionintermediatefollowedbymolecularrearrangementtogiveanester.20.CatalyticReduction

Catalyticreductionof