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Aldehydes have an alkyl, R, or aryl, Ar, group and a hydrogen atom that sandwiches a carbonyl group. A ketone has two groups (alkyl or aryl) sandwiching a carbonyl group. Aldehydes and ketones undergo a series of important reactions. This paper discusses those reactions and their mechanisms. In addition, the paper discusses several syntheses of aldehydes and ketones and their mechanisms.
Citation preview
1
AldehydesandKetones
BuildingBridgestoKnowledge
Photo of the Huanpu River Cruise Boat’s gangplank in Shanghai, China
2
Thestructureofaldehydesandketonescanberepresentedbythefollowinggeneral
formulas.
Aldehydeshaveanalkyl,R,oraryl,Ar,groupandahydrogenatomthatsandwiches
acarbonylgroup.Aketonehastwogroups(alkyloraryl)sandwichingacarbonyl
group.
Followingaresomeexamplesofaldehydesandketones:
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benzaldehyde diphenylketone
(benzophenone)
methylphenylketone
(acetophenone)
n-butanaln-butylethylketone
(3-heptanone)
Innamingaldehydes,oneselectsthelongestcontinuouschaincontaining,and
4
dropthe“e”ofthelongestcontinuousalkanecontainingthealdehydicgroup,and
replacethe“e”with“al.”Thealdehydereceivesnumericalpreferenceoverside
chainsubstituentsand/orcentersofunsaturation.
Followingtheserules,theIUPACnamefor
is4,4-dimethylnonanal.
TheIUPACnamefor
is4-methyl-4-phenyloctanedial
WhenCHO,aformylgroup,isattachedtoaring,theringnameisfollowedbythe
suffix“carbaldehyde.”
Forexample,theIUPACnamefor
Iscyclohexanecarbaldehyde
5
Somefamiliaraldehydesareformaldehyde(I),acetaldehyde(II),andbenzaldehyde
(III):
Suggestnamesforthefollowingaldehydes.
(a)
(b)
Answers
(a) 3-bromo-4-ethoxybenzenecarbaldehyde
(b) (e,e)3-ethylcyclohexanecarbaldehyde
Somefamiliarketonesareacetone(IV);acetophenone(V);benzophenone(VI):
6
Ketonescanbenamedbyselectingthelongestcontinuouschaininthecarbonchain,
includingthecarbonylcarbon,andnamingtheattachedgroupsassubstituents.
Forexample,theIUPACnamefor
is5-hexen-2-one.
TheIUPACnamefor
is2,2-dimethyl-6-phenyl-3-hexanone.
UsingIUPACrulesfornomenclature,suggestnamesforthefollowingketones.
7
(a)
(b)
(c)
(d)
Answers
(a) 6-methyl-5-hepten-2-one
(b) (E)-5-hepten-2-one
(c) 2-methyl-2,6-diphenyl-3-hexanone
(d) (Z)-5-hepten-2-one
8
TheNatureoftheCarbonylGroup
TheC=ObonddistanceisshorterthantheC-Obonddistance.TheH-C-Obondangle
inketonesandaldehydesisapproximately120o.Thehybridizationaroundthe
carbonylcarbonatomsofaldehydesandketonesissp2.
Thegeometryaroundthecarbonylcarbonatomsinaldehydeandketonesistrigonal
planar,andtheC=ObondismorepolarthantheC=Cbond.
PhysicalProperties
Aldehydesandketoneshavehigherboilingpointsthancomparablemolecularmass
alkenes,becausetheintermolecularforcesbetweenaldehydesandketonesare
strongerthantheintermolecularforcesbetweenalkenes.
Aldehydesandketoneshavelowerboilingpointsthancomparablemolecularmass
alcohols,becausealcoholscanmolecularassociatewitheachother.
However,carbonylgroupscanmolecularlyassociatewiththeOHofalcoholsor
phenolsorcarboxylicacidsorwater;therefore,carbonylcompoundsaremore
solubleinwaterthancomparablemolecularmassalkenes.Thesolubilityof
carbonylcompoundsdecreasesinalcohols.
ReactionsofAldehydesandKetones
Aldehydesandketonescanformcyanohydrins.Cynanohydrinsarecompounds
containinganitrilegroup,CN,andahydroxylgroup,OHonthesamecarbonatom.
9
Cyanohydrinsareformedwhenalkalimetalcyanidesreactwiththecarbonylgroup
ofaldehydesandketones.
Cyanohydrinscanbeconvertedtoα-hydroxycarboxylicacidsbyacidifying
cyanohydrins.
Thenetionicequationforthereactionis
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Thefollowingsequenceofreactionsrepresentsaplausiblemechanismfor
explainingtheacidhydrolysisofcyanohydrins.
(1)
(2)
+H2O
(3)
11
(4)
(5)
NaturalCyanohydrins
Naturalcyanohydrinsexistascyanogenicglycosides.Glycosidesareacetals,
geminaldiethers,formedfromnaturalsugarsorsugarderivativesandHOR.
Laetrileisanexampleofaglycoside.
Laetrile
TheIUPACnameforlaetrileis(2S,3S,4S,5R,6R)-6-[(R)-cyano(phenyl)methoxy]-
3,4,5-trihydroxyoxane-2-carboxylicacid.
TheoxaneringortheglucuronicacidstructureofLaetrilecanbevisualizedby
thinkingofanintramolecularnucleophilicattackoftheoxygenatomonthefifth
carbonatomofglucuronicacidwiththealdehydiccarbonylgroupofglucuronicacid
12
toformahemiacetalstructure.Theresultwouldbeasixmemberedheterocyclic
ring(theoxanering).Thisprocessisillustratedbythefollowingequation.
ThefinalstepintheformationofLaetrilewouldbetheformationoftheglycosidic
linkageattheanomericcarbonatom,andthisisillustratedbythefollowing
equation.
O
COOH
OH
H
H
H
H
H
HO
OH
OH
..
.. O
H
H
H
H OH
OH
HOHO
HCO
HO
13
AcetalFormation
Acetalsareformedfromthereactionofalcoholswithaldehydesinthepresenceofa
mineralacid.Thereactionsequenceproceedsfirstthroughtheformationofa
hemiacetal,andthentotheformationoftheacetal.Followingisanillustrationof
theformationofacetals.
O
H
H
H
H OH
OH
HOHO
HCO
HO
+ C
C N :
HHO
HOCOH
HOHO
OH
H
H
H
H
OOH
:NC
C
14
Thesequenceofelementarystepsthatwouldaccountforthisreactionmaybe
visualizedinthefollowingmanner.
(1)
(2)
15
(3)
(4)
(5)
16
(6)
(7)
Diolsinthe1,2and1,3positionsformcyclicacetals(1,3-dioxolanes,5-member
rings,or1,3-dioxane,6-memberrings)withaldehydesandketones.
anacetal(a1,3-dioxolane) 2-phenyl-1,3-dioxane
C
O
+
HO
HO
S
O
O
OHCH3O
O
H H
+ H2O
17
anacetal(a1,3-dioxane)
2-phenyl-1,3-dioxane
Ketonescanalsoundergoreactionswith1,2and1,3diolsanalogoustoaldehydes.
Theresulting1,3-dioxolaneor1,3-dioxanecanbereferredtoasketals.
aketal(a1,3-dioxolane)
2-phenyl-2-methyl-1,3-dioxolane
aketal(a1,3-dioxane)
2-phenyl-2-methyl-1,3-dioxane
Thewaterproducedinthesereactionsisremovedazeotropically*,anddrivesthe
equilibriumtotheright,i.e.,towardthe2-phenyl-1,3-dioxane,the2-phenyl-1,3-
dioxolane,the2-phenyl-2-methyl-1,3-dioxolane,orthe2-phenyl-2-methyl-1,3-
dioxane.
C
O
+
HO
HO
S
O
O
OHCH3O
O + H2O
CH3 H3C
C
O
+
HO
HO
S
O
O
OHCH3
+ H2O
CH3 H3CO
O
18
Acetals/ketalsreadilyhydrolyzeinacidtoformthealdehydeortheketone.This
reaction,forexample,canbeobservedintheacidcatalyzedhydrolysisof2-phenyl-
1,3-dioxane.
Followingisasequenceofelementarystepsthatrationalizethisobservation.
(1)
(2)
(3)
(4)
19
(5)
(6)
20
Acetals/ketalsasProtectiveGroups
Likeethers,theacetal/ketalgroupisunaffectedbymanyreactions;however,
acetals/ketalscanbeconvertedtoaldehydesorketonesbyacidhydrolysis.
Assumeanundergraduateseniorchemistrystudentunderthesupervisionofa
facultyadvisorisinterestedinsynthesizing1-phenyl-3-hexyn-2-onefrom
benzylcarboxylicacid(phenylaceticacid).
phenylaceticacid1-phenyl-3-hexyn-2-one
Thereactioncanbeapproachedbythefollowingretrosynthesis,i.e.,working
backwardstodevelopasynthesisfor1-phenyl-3-hexyn-2-one.
21
22
Usingananalogousprocessastheoneabove,suggestasynthesisforp-acetylbenzyl
alcoholfromp-acetylbenzoicacid
23
p-acetylbenzyalcohol p-acetylbenzoicacid
Answer
Thesynthesisofp-acetylbenzylalcoholusingp-acetylbenzoicacidasaprecursor
canbeaccomplishedinthreesteps.
Step1istheuseof1,3-butandiolasaprotectiveforcarbonyl.
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Step2isthereductionoftheacidwithsodiumborohydride.
Step3isacidhydrolysisofthe1,3-dioxaneringinordertoreleasetheprotective
group.
Theprotectivegroupisrequired,becausesodiumborohydridewouldreducethe
ketonegroupaswellasthecarboxylicacidgroup.
AldehydesandKetonescanreactwithprimaryaminesasindicatedinthefollowing
reactiontoproduceN-substitutedimines.
25
Theproduct,anN-substitutedimine,isformedthroughacarbinolamine
intermediate.
carbinolamineintermediate
Followingisthemechanismforthisreactioninanacidicmedium.
Thereactionisoptimizedat[H3O+]=1x10-5mol/L,i.e.,atpH=5.
AtapHlessthan5,theprimaryaminewillbeprotonatedandhydrogenionswillnot
beavailabletoprotonatethealdehydeortheketone.AtapHgreaterthan5,the
carbocationintheratedeterminingstep(step6)willbenotbeproduced,because
thesolutionwillbetoobasicfortheformationofthepositivecharge.
(1)
26
(2)
(3)
(4)
(5)
(6)
27
(7)
(8)
(9)
Imine-typecompoundsareusefulinthetraditionalidentificationofaldehydesand
ketones.Thesecompoundsarereferredtoasoximes,semicarbozones,
phenylhydrazones,and2,4-dinitrophenylhydrazones.Thesecompoundsandtheir
mechanismswillbediscussedinafuturepaper.Themechanismsofthesereactions
aresimilartotheadditionandeliminationofprimaryaminestocarbonyl
compoundstoformimines.
Oxime
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anoxime
Semicarbazone
asemicarbazone
Phenylhydrazone
29
aphenylhydrazone
2,4-Dinitophenylhydrazone
a2,4-dinitrophenylhydrazone
30
ReactionsofAldehydesandKetoneswithSecondaryAmines
Thereactionofaldehydesandketoneswithsecondaryaminesproceedsviathe
formationofcarbinolamineintermediates,followedbydehydrationtostable
enamines(alkenyl-substitutedamines).
31
Thefollowingsequenceofthreeelementarystepsrepresentsthemechanismthat
wouldrationalizetheformationoftheenamine.
(1)
(2)
(3)
(4)
32
Theenamine
TheWittigReaction
TheWittigreactionisamethodforconvertingaldehydesandketonestoalkenesvia
theuseofaphosphorusylideslikemethylenetriphenylphosporane.
Thereactionisgenerallycarriedoutinaproticsolventslikedimethylsulfoxide
(DMSO)ortetrahydrofuran.
DMSO
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FollowingisaproposedmechanismfortheWittigreaction.
(1)
(2)
(3)
34
oxaphosphetane
(4)
(5)
ThephosphorusylideispreparedfromanalkylhalidebyanSN2reaction.
Theresultingmethyltriphenylphosphoniumiodidecrystallizesinhighyieldfrom
nonpolarsolvents.Thesaltisisolated,andconvertedtothedesiredylidebya
strongbasesuchasthesodiumsaltofdimethylsulfoxideororganolithiumreagents.
35
Phosphorusylidesareexcellentprecursorsforplanningsynthesesforalkenes.For
example,thesynthesisof3-ethyl-4-methyl-3-hexenecanberetrosynthetically
executedinthreesteps.
Step3isthereactionoftheylidewiththedesiredketonetoform3-ethyl-4-methyl-
3-hexene.
36
Step2isthepreparationoftheylidefromthephosphoniumiodidesalt,3-
pentyltriphenylphosphoniumiodide,andastrongbase,lithiumethide.
Step1isthesynthesisof3-pentyltriphenylphosphoniumiodide,theprecursorto
theylide,fromtriphenylphosphineandanappropriatealkylhalide,3-iodopentane.
37
IodoformReaction
Methylketones,aswellasmethylgroupsattachedtocarbonatomsforminga
secondaryalcohol,reactwithiodineinsodiumhydroxidetoformayellow
precipitate.Thereactionofmethylketoneswithiodineinsodiumhydroxideis
referredtoastheiodoformreaction.Theyellowprecipitateistriiodomethaneor
iodoform,thenamethatgivesrisetothenomenclatureofthereactionFollowingis
anexampleoftheiodoformreactionshowingthestoichiometryofthereaction.The
stoichiometryofthereactiongivesinsightintotheseriesofelementarystepthat
couldrationalizetheformationoftheproducts.
38
Thefollowingseriesofelementarystepsexplainhowmethylketonescanform
iodoform(ayellowprecipitate).
(1)
(2)
(3)
39
(4)
(5)
(6)
(7)
(8)
40
(9)
(10)
(11)
yellowprecipitate
Thesumoftheelementarysteps1-11gives
41
Ketoneswithmethylgroupsattachedwillreactwithiodineandsodiumhydroxide
togiveayellowprecipitate,iodoform.Secondaryalcoholswithmethylgroups
attachedwillalsoreactwithiodineandsodiumhydroxidetoproduceiodoform.
Theformationoftheyellowprecipitateisreferredtoasapositiveiodoformtest.
Similarreactionswilloccurwhenmethylketonesorsecondaryalcoholsarereacted
withchlorineandsodiumhydroxide.Also,similarreactionswilloccurwhenmethyl
ketonesorsecondaryalcoholswithmethylgroupsattachedreactwithNaOHand
bromine.However,theresultingchloroformandbromoformmoleculesarenot
precipitateswithdramaticcolorsasiodoform.
TheCannizzaroReaction
TheCannizzaroreactionisnamedafteritsdiscovererStanislaoCannizzarowho
discovereditsometimeduringthemiddleofthenineteenthcentury.Thereaction
involvesthebase-induceddisproportionationofanaldehydethatdoesn’thavea
hydrogenatomattachedtothealphacarbonatom.Theproductsofthe
disproportionationreactionarethesaltofacarboxylicacid,theoxidationproduct,
andanalcohol,thereductionproduct.FollowingisanexampleoftheCannizzaro
Reaction.
OH
CH3(R or Ar)C
H
+ I2 NaOH+
C(R or Ar)
O
H
+ +
3 3
3 3H2O NaI CHI3+
42
FollowingisthemechanismoftheCannizzaroreaction.
(1)
(2)
(3)
StereoselectiveAdditiontoCarbonylGroups
Nucleophilicadditiontocarbonylgroupscangiverisetostereoisomericproducts.
Stericfactorsplayamajorroleintheresultingproductwherethenucleophile
approachesthecarbonylatthelesshindereddirection.
Forexample,treating7,7-diethylbicyclo[2.2.1]heptan-2-onecangiverisetotwo
possibleproducts-exo-7,7-diethylbicyclo[2.2.1]heptan-2-olorendo-7,7-
diethylbicyclo[2.2.1]heptan-2-ol.Theexo-7,7-diethylbicyclo[2.2.1]heptan-2-ol
43
wouldbethepredominantproduct,becausethetwoethylgroupswouldhinderthe
approachoftheBH4-anionfromtheendoposition;consequently,theexoproduct
wouldpredominate.
Therefore,thereductionproductisstereoselective.Thepreferredattachisendo
whichleadstotheexoproduct.Exoattackwouldleadtotheendoproduct.Both
productsaretheoreticallypossible,but,inthiscase,theexoproductpredominates.
44
Ifthereactionisenzyme-catalyzed,thenonewouldexpectthattheoneofthetwo
possiblestereoisomerswouldbeexclusivelyformed.Forexample,whenpyruvic
acidisconvertedtolacticacidviatheenzymelactatedehydrogenaseandits
coenzyme,reducedformofnicotinimideadeninedinucleotide,NADH,the
predominateproductistheS-configurationwhichisdetrorotatory,i.e.,(S)-(+)-lactic
acidexclusively.
TheBaeyer-VilligerOxidationofKetones
TheBaeyer-Villigerreactionisthesynthesisofanesterfromaketone,andAdolfvon
BaeyerandVictorVilligerreportedthereactionin1899.Ketonesreactwith
peroxyacidstoinsertanoxygenatombetweenthecarbonylgroupandthelargerof
twoattachedalkylorarylgroupstoformanester.Forexample,
MethylchlorideisonesolventthatmaybeusedintheBaeyer-Villigeroxidation
reactions.
Theseriesofelementarystepsthatleadtotheformationoftheesterincludesthe
migrationofthealkylgroupwithretentionofconfiguration;therefore,if
45
stereochemistryispossible,thereactionleadstotheretentionofconfiguration,i.e.,
thereactionisstereospecific.
(1)
(2)
Sincethealkylgroupmigrateswithretentionofconfiguration,trans-(e,e)-4-
methylcyclohexylmethylketonewouldformtrans-(e,e)-4-methylcyclohexylacetate
astheexclusivestereospecificproduct.
46
ReformatskyReaction
Aldehydesandketonescanreactwithα-haloestersinthepresenceofmetalliczinc
toformβ-hydroxyesters.Thefollowingrepresentsareactionbetweenmethylethyl
ketoneandethylα-bromoacetateinthepresenceofzinctoproduceethyl3-
hydroxy-3-methylpentanoate.
Followingaretheseriesofelementarystepstorationalizetheformationofthe
productfortheReformatskyreactionusingtheabovereactionasamodel.
(1) Zincrelinquishestwoelectronstoethyl2-bromoacetatetoproducea
zincbromoenolate.
47
(2) Thezincbromoenolatereactswith2-butanonetogivethezincbromosaltof
ethyl3-methyl-3-hydroxypentanoate.
Acidhydrolysisofthezincbromoenolatewouldformtheproduct,ethyl3-methyl-3-
hydroxypentanoate.
*AzeotropicDistillation
Anyofseveralprocessesbywhichliquidmixturescontainingazeotropesmaybeseparatedintotheirpurecomponentswiththeaidofanadditionalsubstance(calledtheentrainer,thesolvent,orthemassseparatingagent)tofacilitatethedistillation.Distillationisaseparationtechniquethatexploitsthefactthatwhenaliquidispartiallyvaporizedthecompositionsofthetwophasesaredifferent.Byseparatingthephases,andrepeatingtheprocedure,itisoftenpossibletoseparatetheoriginalmixturecompletely.However,manymixturesexhibitspecialstates,knownasazeotropes,atwhichthecomposition,temperature,andpressureoftheliquidphasebecomeequaltothoseofthevaporphase.Thus,furtherseparationbyconventionaldistillationisnolongerpossible.Byaddingacarefullyselectedentrainertothemixture,itisoftenpossibleto“break”theazeotropeandtherebyachievethedesiredseparation.
Entrainersfallintoatleastfourdistinctcategoriesthatmaybeidentifiedbythewayinwhichtheymaketheseparationpossible.Thesecategoriesare:(1)liquidentrainersthatdonotinduceliquid-phaseseparation,usedinhomogeneousazeotropicdistillations,ofwhichclassicalextractivedistillationisaspecialcase;(2)liquidentrainersthatdoinducealiquid-phaseseparation,usedinheterogeneousazeotropicdistillations;(3)entrainersthatreactwithoneofthecomponents;and(4)entrainersthatdissociateionically,thatis,salts.SeeSalt-effectdistillation
Withineachofthesecategories,notallentrainerswillmaketheseparationpossible,thatis,notallentrainerswillbreaktheazeotrope.Inordertodeterminewhethera
48
givenentrainerisfeasible,aschematicrepresentationknownasaresiduecurvemapforamixtureundergoingsimpledistillationiscreated.Thepathofliquidcompositionsstartingfromsomeinitialpointistheresiduecurve.Thecollectionofallsuchcurvesforagivenmixtureisknownasaresiduecurvemap(seeillustration).Thesemapscontainexactlythesameinformationasthecorrespondingphasediagramforthemixture,buttheyrepresentitinsuchawaythatitismoreusefulforunderstandinganddesigningdistillationsystems.
http://encyclopedia2.thefreedictionary.com/azeotropic+distillation
49
Problems
AldehydesandKetones
1. SuggestIUPACnamesforthefollowingmolecules.
(a)
(b)
(c)
2. Suggestamechanismforthefollowingconversion.
50
3. Suggesttheproductexpectedfromthereactionofbenzaldehydewitheachofthe
following.
(a)
(b) dilutesodiumhydroxide
(c) concentratedsodiumhydroxide
(d) propanalanddilutehydroxide
(e) butanalanddilutesodiumhydroxide
(f)
51
4. Suggestasynthesisforthefollowingmoleculefromtheindicatedstarting
materialandanynecessaryorganicandinorganicmaterials.
5. Writeamechanismforyoursynthesisoftheesterinproblem4.
6. Using1-propanolastheonlysourceoforganiccompoundsandanyother
necessaryinorganicreagents,suggestsynthesesforthefollowing.
(a)
(b)
7. Suggestasynthesisforthefollowingmoleculefromtheindicatedorganic
compoundandanyotheravailableinorganicmaterials.
52
8. Suggestasynthesisforthefollowingfromtheindicatedstartingmaterialand
anynecessaryinorganicandorganiccompounds.
9. CompoundIexhibitsthefollowingprotonmagneticresonancespectrum.
1HNMRofcompoundI
AconstitutionalisomerofcompoundI,compoundII,exhibitsthe
followingprotonmagneticspectrum.
53
1HNMRofcompoundII
WhencompoundIwastreatedwithlithiumaluminumhydride
followedbyhydrolysis,thenaqueousacidatabout200oC,
compoundIII,C10H12wasproduced.CompoundIIIhastwo
isomers.
FollowingistheprotonmagneticresonancespectrumofcompoundIII,C10H12
1HNMRofcompoundIII
54
WhencompoundIIwastreatedwithlithiumaluminumhydridefollowedby
hydrolysis,thenaqueousacidatabout200oC,compoundIV,C10H12was
produced.Followingistheprotonmagneticresonancespectrumof
compoundIV,C10H12.CompoundIVhasoneisomer.CompoundsIIIandIV
arealsoconstitutionalisomers.
1HNMRofcompoundIV
SuggeststructuralformulasforcompoundsI,II,III,andIV.
10. Acertainbiologicallyactiveterpene,C10H16Ofollowstheisoprenerulewillform
anoxime,asemicarbozide,anda2,4-dintrophenylhyradazide.Uponozonolysis,
theterpenesproducesthefollowingcompounds
Suggestastructureconsistentwiththeexperimentaldataandtheisoprene
rule.
11. Aterpenethatfollowstheisopreneruledecolorizesadilutesolutionof
potassiumpermanganate,and,upon,treatmentwithhotconcentrated
55
potassiumpermanganateinsulfuricacid,producesthefollowingtwoorganic
acidsacids:
Suggestastructurefortheterpenethatisconsistentwiththe
experimentalevidence.
12. Suggestasynthesisforthefollowingconversionusingappropriateinorganic
reagents.
13. Suggestaseriesofelementarystepsthatwouldrationalizethefollowing
observations.
(a)
56
(b)
14. Predicttheproductorproductsexpectedinthefollowingsequenceofreactions.
15. CompoundIistreatedwiththereagentsoftheClemmensenreductionto
producecompoundII.TreatingcompoundIIwiththereagentsfor
hydroboration-oxidationproducescompoundIII.CompoundIIIupon
treatmentwithpyridiniumchlorochromateproducescompoundIV.
CompoundI
SuggeststructuralformulasforcompoundsII,III,andIV.
16.
Considerthefollowingsynthesispathway:
CH3CH2
C
O
CH2CH2C
OH
O
+ 1,3-propandiolH3O
+C9H16O4
57
SuggeststructuresofC9H16O4;C9H18O3;C6H12O2;andC6H10O2.
17. Treatingcompound17A,C6H12O,withiodineinsodiumhydroxide,resultsin
theformationayellowprecipitateandcompound17B,C5H9O2Na.Acidification
ofcompound17BformedC5H10O2,compound17C.Treatingcompound17C
withLiAlH4followedbyhydrolysisproducescompound17D.Theinfrared
spectrumofcompound17Dexhibitedaprominentstretchingtransmittance
signalat3333cm-1.Followingaretheprotonmagneticresonancespectrum
andcarbon-13magneticresonancespectrumofcompound17D.
C9H16O4 + LiAlH4H2O
C9H18O3
C9H18O3H3O
+C6H12O2
C6H10O2C6H12O2 + PDC
58
1HNMRCompound17D
13CNMRCompound17D
Sulfuricacidconvertedcompound17Dtocompound17E.Ozonolysisofcompound
17Egavecompound17Fand17G.Prominentmassspectrumpeaksforcompound
17Foccuratm/e29and43.Prominentmassspectrumpeaksforcompound17G
occuratm/e43and58.
59
Usethesedatatodeterminethestructuresofcompounds17A,17B,17C,17D,17
E,17F,and17G.Pleasesupportyouranswerswithchemicalequationsandany
givenspectradata.
Provideadetailedmechanismfortheconversionof17Dto17Ewithsulfuricacid.