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Chemistry233Chapter11ProblemSet–Pt.1(SubstitutionReactions)
1. ConsidertheSN2reactionshownbelowandanswerthefollowingquestions.
A. Writetheratelawforthereaction.
B. Identifythenucleophileandtheelectrophileinthereaction.
C. Statehoweachofthefollowingfactorswouldaffecttherateofthereaction.a. Increasingtheconcentrationof1-bromopropane.
b. DecreasingtheconcentrationofNaSCH3byone-half.
c. Changing1-bromopropaneto2-bromopropane.
d. Changing1-bromopropaneto1-iodopropane.
e. ChangingNaSCH3toCH3OH.
2. ConsidertheSN1reactionshownbelowandanswerthefollowingquestions.
A. Writetheratelawforthereaction.
B. Identifythenucleophile,theelectrophile,andthereactionsolvent.
C. Statehoweachofthefollowingfactorswouldaffecttherateofthereaction.a. Increasingtheconcentrationofthealkylhalide.
b. IncreasingtheconcentrationofHOCH3.
c. ReplacingHOCH3withNaOCH3.
d. Changingthealkylhalidefromabromidetoaniodide.
e. Changingthealkylhalideto1-bromopropane.
Br + NaSCH3
acetone SCH3
+ Na + Br
PhBr + HOCH3 Ph
OCH3 + HBr
Chem.233–Chapter11-Pt.1ProblemSet
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3. Foreachofthefollowingpairs,circletheonethatwillproceedfasterbyanSN2reactionmechanism.
4. Foreachofthefollowingpairs,circletheonethatwillproceedfasterbyanSN1reactionmechanism.
F Br
Br Br
Cl Cl
Br + NaSCH3 Br + HSCH3
Br + NaF Br + NaIpolar protic solvent polar protic solvent
Br + NaFpolar aprotic solvent
Br + NaIpolar aprotic solvent
Cl+ NaOH
polar aprotic solvent
Cl+ NaSCH3
polar aprotic solvent
Br + KI (high conc) Br + KI (low conc)
vs
vs
vs
vs
vs
vs
vs
vs
BrBr
Cl Cl+ OH + OH
(high conc)(low conc)
Cl I
I I+ +NH3 NH2
Br Br+ HOEt
(Solvent) + HOEt (1 equiv)THF (solvent)
vs
vs
vs
vs
vs
vs
Br Br
Chem.233–Chapter11-Pt.1ProblemSet
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5. Explainwhythetworeactionsbelowprovideconstitutionallydifferentproducts.
6. Assumingeachreactionbelowundergoesnucleophilicsubstation,predictthemechanism(SN1orSN2)anddrawthemajorproduct.Includestereochemistrywhereappropriate.
Br
Br
HOCH3H3CO
NaOCH3
OCH3
Br
NaOH
NaOHBr
INaCN
ClNH3
Br NaSCH3
DMF
Br HO
I
I
OCH3
HOCH3
DMSO
Acetone
DMSO
Chem.233–Chapter11-Pt.1ProblemSet
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7. ThecompoundbelowcanundergoanintramolecularnucleophilicsubstitutionviaanSN2mechanism.Drawtheproductandthemechanismbywhichitisformed.
8. Explainwhythereactionbelowdoesnotprovideanyproductsfromnucleophilicsubstation.
HSEt
OH
H2O
HO
OCH3
HOCH3
DMSO
Br
DMSO
I
IH
Br
Br H2O
Br
Br
NH
Cl DMF
Br+ ONa
(NaOt-Bu)
No Substitution Reaction
Chem.233–Chapter11-Pt.1ProblemSet
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9. Predicttheproduct(s),withcorrectstereochemistryforeachofthefollowingsubstitutionreactionsinvolvinganalcoholstartingmaterial.
10. Showthecompleteelectronpushingmechanismforthereactioninquestion9a.
11. Showthecompleteelectronpushingmechanismforthereactioninquestion9d.
OH 1. TsCl Pyr2. NaBr
OH HBr
OHHI
OH
1. TsCl Pyr2. NaBr
NaITHF
OH
(a)
(b)
(c)
(e)
(f)
OHHBr
(d)
