Chemistry233
Chapter13:NMRSpectroscopyProblemSet
1) Foreachcompoundbelow,identifyeachchemicallydistincttypeofhydrogen.Specifythenumber
of1HNMRsignalsyouwouldexpecttosee.
O
O
O
H
H
O
O
Br
Cl
CH 3
O
OH
2) Whichoftheindicatedprotonsineachpairshowsupfartherdownfield?
Tips: ForH-C-Z,HmovesfurtherdownfieldasZbecomesmoreelectronegative
ForCsp3-H,HmovesfurtherdownfieldasCbecomesmoresubstituted(3°>2°>1°)
or
O
or
I
F
H
or
CH 3
or
or
H
H
O
H
or
H
H
Chapter13ProblemSet
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3) Considertheindicatedprotonsineachofthethreecompoundsbelow.Arrangeinorderof
increasingchemicalshiftoftheindicatedproton.SeetipsinQ2.
O
O
H
O
H
H
A
B
C
4) Foreachofthecompoundsbelow,determinetheexpectedsplittingforallprotons.
O
O
OH
O
H
O
Cl
OH
H
O
13
5) Howmany Csignalswouldyouexpecteachcompoundbelowtoexhibit?(i.e.Howmany
chemicallydistinctCatomsarepresentineachmolecule?)
O
F
H
Cl
O
OH
O
Br
Cl
6) AsymmetricdiesterhastheformulaC6H10O4andthefollowing1HNMRspectraldata:1.47(d,3H),
2.07(s,6H),6.84(q,1H).Proposeastructureforthiscompound.
Chapter13ProblemSet
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7) Thereactionshownbelowwascarriedoutinalaboratorytogiveacompoundwiththeindicated
spectraldata.Determinethestructureofthiscompound.
C11H15NO 2
IR stretch at 1730 cm-1
Eight signals in the 13 C NMR
1H 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)
O
H
N
+
OH
F
8) Foreachofthefollowing,usethedataprovidedtodeduceanappropriatestructure.
A. C6H12
3H
3H
2H
1H
6
2H
1H
5
4
3
PPM
2
1
0
Chapter13ProblemSet
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B. C5H9ClO2
Usethe13CNMRtodeterminethenumberofdistinctCatoms.
IRspectroscopyshowsastrongC=Ostretch.
1H
NMR
3H
2H
2H
2H
5
4
13C
180
3
PPM
2
1
0
NMR
160
140
120
100
PPM
80
60
40
20
0
C. C6H10
1H
9H
NMR
1H
3
2
PPM
1
0
Chapter13ProblemSet
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D. C4H6O2
IRshowsastrongstretchat1740cm-1
1H
NMR
2H
2H
2H
5
4
3
PPM
2
1
0
E. C4H8O2
1H
NMR
septet
10
8
6
4
PPM
2
0
F. C6H12
1H
6
NMR
2
5
Chapter13ProblemSet
4
4
3
PPM
2
1
0
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G. Compoundcontains10CandIRshowsastrongstretcharound1690cm-1
1H
3H
NMR
2H
5H
2H
9
8
7
6
5
PPM
4
3
2
1
0
H. C4H9OCl
3
2
2
2
4
3
2
PPM
1
0
Chapter13ProblemSet
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9) Foreachofthecompoundsbelow,drawaroughestimationofitsexpected1HNMRspectrum.
Cl
Cl
Cl
O
I
Br
Br ChallengeProblems:
10)Usethespectraldataprovidedtopredicttheproductofthereactionshownbelow.
OH
H 3O+
OH
H 2O
C 7H12O
IR: 1729 cm-1
1H 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.
11)Thevinylprotonchemicalshiftinthetwocompoundsshownbelowissubstantiallydifferent.
Explainwhytheshiftinthesetwocompoundsissodifferent.Hint:thinkaboutresonance.
O
O
H
CH 3
H
4.0 ppm
6.5 ppm
Chapter13ProblemSet
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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,howwouldyouexpectittochangefollowingthe
reaction?Note:DisaheavyisotopeofH.ItreactsalmostidenticallytoH(ie.DClreactslikeHCl).
O
1. NaH
2. DCl, D 2O
OH
O
OH
12
10
8
6
PPM
4
2
0
14)Thestructureofcubaneisshownbelow.Whatisthemolecularformulaforcubane?Usingthe
unsaturationcalculation,determinethedegreesofunsaturation.Now,usingvisualinspection,
determinethedegreesofunsaturation.Youshouldfindthatthereisadiscrepancy.Whichnumber
iscorrect?Canyouuseanalternatemethodtoconfirmyourunsaturationcount?
Chapter13ProblemSet
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