Aldehydes and Ketones, Building Bridges to Knowledge

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:

3

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

10

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.

24

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

28

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

33

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.