Chapter13ProblemSet 1/8

Chemistry233Chapter13:NMRSpectroscopyProblemSet

1) Foreachcompoundbelow,identifyeachchemicallydistincttypeofhydrogen.Specifythenumber

of1HNMRsignalsyouwouldexpecttosee.

2) Whichoftheindicatedprotonsineachpairshowsupfartherdownfield?Tips: ForH-C-Z,HmovesfurtherdownfieldasZbecomesmoreelectronegative ForCsp3-H,HmovesfurtherdownfieldasCbecomesmoresubstituted(3°>2°>1°)

H

O O

O

O

O

Cl

CH3

Br

OH

O

H

O

I F H

CH3

H

HH O

H H

or or

or or

or or

Chapter13ProblemSet 2/8

3) Considertheindicatedprotonsineachofthethreecompoundsbelow.Arrangeinorderofincreasingchemicalshiftoftheindicatedproton.SeetipsinQ2.

4) Foreachofthecompoundsbelow,determinetheexpectedsplittingforallprotons.

5) Howmany13Csignalswouldyouexpecteachcompoundbelowtoexhibit?(i.e.HowmanychemicallydistinctCatomsarepresentineachmolecule?)

6) AsymmetricdiesterhastheformulaC6H10O4andthefollowing1HNMRspectraldata:1.47(d,3H),2.07(s,6H),6.84(q,1H).Proposeastructureforthiscompound.

OO O

HH H

A B C

O

OOH

H

O

OOH

O

ClH

H

O

OO

Br

Cl

Cl

F

OH

Chapter13ProblemSet 3/8

7) Thereactionshownbelowwascarriedoutinalaboratorytogiveacompoundwiththeindicatedspectraldata.Determinethestructureofthiscompound.

8) Foreachofthefollowing,usethedataprovidedtodeduceanappropriatestructure.A. C6H12

F

H

O

+ NOH

C11H15NO2IR stretch at 1730 cm-1

Eight signals in the 13C NMR1H NMR Data: 2.32 (s, 6H), 3.05 (t, 2H), 4.20 (t, 2H), 6.97 (d, 2H), 7.82 (d, 2H), 9.97 (s, 1H)

0123456PPM

1H 1H

2H2H

3H

3H

Chapter13ProblemSet 4/8

B. C5H9ClO2 Usethe13CNMRtodeterminethenumberofdistinctCatoms.IRspectroscopyshowsastrongC=Ostretch.

C. C6H10

012345PPM

2H

3H

2H2H

1H NMR

020406080100120140160180PPM

13C NMR

0123PPM

1H

9H1H NMR

Chapter13ProblemSet 5/8

D. C4H6O2

IRshowsastrongstretchat1740cm-1

E. C4H8O2

F. C6H12

012345PPM

1H NMR 2H

2H

2H

0246810PPM

1H NMR

septet

012345PPM

24

61H NMR

Chapter13ProblemSet 6/8

G. Compoundcontains10CandIRshowsastrongstretcharound1690cm-1

H. C4H9OCl

0123456789PPM

1H NMR

5H

2H

2H

3H

01234PPM

2 2

3

2

Chapter13ProblemSet 7/8

9) Foreachofthecompoundsbelow,drawaroughestimationofitsexpected1HNMRspectrum.

ChallengeProblems:10) Usethespectraldataprovidedtopredicttheproductofthereactionshownbelow.

11) Thevinylprotonchemicalshiftinthetwocompoundsshownbelowissubstantiallydifferent.Explainwhytheshiftinthesetwocompoundsissodifferent.Hint:thinkaboutresonance.

Cl

ClCl O

I Br Br

OH

OHH3O+

H2OC7H12O

IR: 1729 cm-11H NMR: 9.72 (d, 1H), 2.30 (sex, 1H),1.4-18 (m, 10H)

signals for 10 H overlapping in this region. Some are and some are not

equivalent.

O

O

H

H

CH3 4.0 ppm6.5 ppm

Chapter13ProblemSet 8/8

12) ProposeastructureforacompoundwiththeformulaC5H9ClO.1HNMRData: δ6.07(1H,multiplet)alkeneH δ5.43(1H,d)alkeneH δ5.31(1H,d)alkeneH δ4.04(2H,d) δ3.83(2H,t) δ3.65(2H,t)

13) Astudentranthereactionshownbelow.Whatwouldyouexpectthestructureoftheproducttobe?

Giventhe1HNMRofthestartingmaterials,howwouldyouexpectittochangefollowingthereaction?Note:DisaheavyisotopeofH.ItreactsalmostidenticallytoH(ie.DClreactslikeHCl).

14) Thestructureofcubaneisshownbelow.Whatisthemolecularformulaforcubane?Usingtheunsaturationcalculation,determinethedegreesofunsaturation.Now,usingvisualinspection,determinethedegreesofunsaturation.Youshouldfindthatthereisadiscrepancy.Whichnumberiscorrect?Canyouuseanalternatemethodtoconfirmyourunsaturationcount?

OH

O 1. NaH

2. DCl, D2O

024681012PPM

OH

O