說明分析內(nèi)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(永久偶極)?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鋁氫化鋰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(特性檢測(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)（酒石酸銅）ItisablueAliphaticaldehydesreducetheCu2+ioninFehling’ssolutiontoformabrick-redprecipitateofCu2O?AdditionofanaliphaticFehling’sAdditionofanaliphaticFehling’s ?KetonesandaromaticaldehydesgiveanegativeresultofFehling’stestThisreactioncanbeusedtodistinguishaliphaticaldehydesfromketonesandaromaticaldehydes?DistinguishingbetweenaldehydesandOxidizingObservationonoxidationofanExplanationofDistinguishingbetweenaldehydesandOxidizingObservationonoxidationofanExplanationof(酸性高錳酸鉀thepurplesolutionturnsthepurplemanganate(VII)ion,isreducedtocolourless.(酸性重鉻酸鉀theorangesolutionturnsgreenCrOisreducedto chromium(III)ion,Fehling’ssolution(analkalinesolutionofCu2+complexred,theCu2+ionisreducedtoredaqueoussolutionofsilvernitrateinexcessammonia)asilvermirrorformsonthesidesofthetesttubefromthecolourlessthesilver(I)ionisreducedtosilvermetalDistinguishingbetweenaldehydesandOxidizingObservationonoxidationofanExplanationofDistinguishingbetweenaldehydesandOxidizingObservationonoxidationofanExplanationofacidifiedpotassium(酸性高錳酸鉀boilgentlythepurplesolutionturnsthepurplemanganate(VII)ion,isreducedtocolourless.acidifiedpotassium(酸性重鉻酸鉀boilgentlytheorangesolutionturnsgreentheoranged