说明分析内容

Carbonylcompounds,Carbonylcompounds,GeneralformulaofGeneralformulaof•Thethree•ThethreeatomsthatarebondedtothecarbonylcarbonformsatrigonalplanarstructureThebondanglesbetweenthreeattachedatomsare•Aldehydesarenamedbyreplacingthefinal“-e”ofthenameofthecorrespondingalkanewith“-al”KetonesKetonesarenamedbyreplacingthefinal“-e”ofthenameofthecorrespondingalkanewith“-one”.Theparentchainisthennumberedinthewaythatgivesthecarbonylcarbonatomthelowestpossiblenumber,andthisnumberisusedtoindicateitsposition.••StructureStructuralStructureStructuralPentan-2-Pentan-3-1.Physical(1)1.Physical(1)Boiling No.ofcarbon:theboilingpointofalkenesincreaseasthechainlengthincrease;Straightchain>branchedchain:alkeneswithbranchedchainshavelowerboilingpointthanstraightchainalkeneswiththesamenumberofcarbonatoms.Lessbranchedchain>branchedchain:thenumberofbranchesinthechainincrease,theboilingpointdecrease.Reason:theypacktogetherverywell,sotheyhavestrongerintermolecularforces.ivivSimilarMrhighermeltingandboilingpointsthanalkanesofcomparableMr,theyarepolarmolecules,havingpermanentdipole(永久偶极)•Carbonylcompoundshavehigherb.p.andm.p.thanhydrocarbonsofsimilar•Carbonylcompoundshavehigherb.p.andm.p.thanhydrocarbonsofsimilarrelativemolecularmasses∵thepresenceofdipole-dipole•Carbonylcompoundshaveb.p.andm.p.thanthe∵dipole-dipoleinteractionsareweakerthanintermolecularhydrogenAldehydesandAldehydesandketonesoflowmolecularmassesappreciablesolubilitiesinbecausecarbonyloxygencanformstronghydrogenbondswithwaterpanoneandethanalaresolubleinwaterinallThesolubilityThesolubilityofcarbonylcompoundsinwaterdecreasewithincreasingcarbonchainlength.thenon-polarcontributiontothemoleculebecomesmore3.ofExample3.ofExampleofoxidizingagents:acidified•Aldehydesarepreparedbyoxidationof1°Ketonesarepreparedbyoxidationof2°•4.Chemical4.Chemical••OxygenismoreThecarbonyloxygenbearsapartialnegativeandthecarbonylcarbonbearspartialpositiveCarbonylgroupisCarbonylgroupissusceptibletonucleophilic∵carbonylcarbonbearsapartialpositiveNucleophilesuseitslonepairelectronstoformabondwithcarbonylcarbonOnepairofbondingelectronsofthecarbon-oxygenbondshiftouttothecarbonyloxygen•••TheTheelectron-richoxygentransfersitselectronpairtoaadditionofNu–HtothecarbonylAdditionofAdditionofhydrogencyanidetothecarbonylbothaldehydesbothaldehydesandketoneswillreactwithhydrogencyanidecatalyst:Reason:hydrogencyanideisaweakacidandthepresenceofabaseincreasetheconcentrationofcyanideions.2-iv)MechanismforthenucleophilicadditionMechanismforthenucleophilicadditionofhydrogencyanidetocarbonyl2-Hydroxyalkanenitrilesare2-Hydroxyalkanenitrilesareusefulintermediatesinorganici)Onacidhydrolysis,2-hydroxyalkanenitrilesareconvertedto2-hydroxycarboxylicacidsor2-alkenoicacids2)With2)Withtheuseofreducingagentse.g.LiAlH4铝氢化锂2-hydroxyalkanenitrilesarereducedtoaldehydesareoxidisedaldehydesareoxidisedfurthertocarboxylicacids.（醛被氧化成酸ketonesarenotoxidisedtocarboxylicacids.（酮不能被氧化成酸•Lithiumtetrahydridoaluminate(also•Lithiumtetrahydridoaluminate(alsocalledlithiumaluminiumhydride,LiAlH4)isapowerfulreducingagent•Itreducesaldehydesto1°alcoholsandketonesto2°LiAlH4isLiAlH4isabletoreducecarboxylicacidandesterstogive•LiAlH4reactsviolentlywithwater,thereforethereactionmustcarriedoutinanhydroussolutions,usuallyindry•Inpractice,Inpractice,thereductionofaldehydesandketonestoalcoholsiscarriedoutbysodiumtetrahydridoborate(alsocalledsodiumborohydride,NaBH4isaNaBH4isalesspowerfulreducingagentthan•NaBH4reducesonlyaldehydesand•ThereductionbyNaBH4canbecarriedoutinwateror•3.Characteristic3.Characteristictests(特性检测(1)atestforthepresenceofthecarbonylreagent:2,4-dinitrophenylhydrazine(2,4-二硝基苯肼observation:adeepyellowororangeAg(NH3)2+oxidizesaldehydestocarboxylicwhileitisreducedtometallicsilverwhichdepositsonthewallofthereactionvesselassilvermirror•••Aldehydesaremixedwith•AldehydesaremixedwithTollens’reagentinacleantesttubeandplacedinwaterbathkeptat60C•Ifthewallofthereactionvesselisnotcleanenough,asilvermirrorcannotbeformedandablackprecipitateisdepositedinstead•AllketonesgiveanegativeresultofthesilvermirrortestThisreactioncanbeusedtodistinguishaldehydesfromketones••Fehling’ssolutionis•Fehling’ssolutionisanalkalinesolutionofcopper(II)（酒石酸铜）ItisablueAliphaticaldehydesreducetheCu2+ioninFehling’ssolutiontoformabrick-redprecipitateofCu2O•AdditionofanaliphaticFehling’sAdditionofanaliphaticFehling’s •KetonesandaromaticaldehydesgiveanegativeresultofFehling’stestThisreactioncanbeusedtodistinguishaliphaticaldehydesfromketonesandaromaticaldehydes•DistinguishingbetweenaldehydesandOxidizingObservationonoxidationofanExplanationofDistinguishingbetweenaldehydesandOxidizingObservationonoxidationofanExplanationof(酸性高锰酸钾thepurplesolutionturnsthepurplemanganate(VII)ion,isreducedtocolourless.(酸性重铬酸钾theorangesolutionturnsgreenCrOisreducedto chromium(III)ion,Fehling’ssolution(analkalinesolutionofCu2+complexred,theCu2+ionisreducedtoredaqueoussolutionofsilvernitrateinexcessammonia)asilvermirrorformsonthesidesofthetesttubefromthecolourlessthesilver(I)ionisreducedtosilvermetalDistinguishingbetweenaldehydesandOxidizingObservationonoxidationofanExplanationofDistinguishingbetweenaldehydesandOxidizingObservationonoxidationofanExplanationofacidifiedpotassium(酸性高锰酸钾boilgentlythepurplesolutionturnsthepurplemanganate(VII)ion,isreducedtocolourless.acidifiedpotassium(酸性重铬酸钾boilgentlytheorangesolutionturnsgreentheoranged