Chemistry233
Chapter11ProblemSet–Pt.1(SubstitutionReactions)
1. ConsidertheSN2reactionshownbelowandanswerthefollowingquestions.
Br
acetone
+
S
NaSCH 3
CH 3
+
Na
A. Writetheratelawforthereaction.
B. Identifythenucleophileandtheelectrophileinthereaction.
C. Statehoweachofthefollowingfactorswouldaffecttherateofthereaction.
a. Increasingtheconcentrationof1-bromopropane.
b. DecreasingtheconcentrationofNaSCH3byone-half.
+
Br
c. Changing1-bromopropaneto2-bromopropane.
d. Changing1-bromopropaneto1-iodopropane.
e. ChangingNaSCH3toCH3OH.
2. ConsidertheSN1reactionshownbelowandanswerthefollowingquestions.
Br
+
HOCH 3
O
CH 3
+
HBr
A. Writetheratelawforthereaction.
B. Identifythenucleophile,theelectrophile,andthereactionsolvent.
C. Statehoweachofthefollowingfactorswouldaffecttherateofthereaction.
a. Increasingtheconcentrationofthealkylhalide.
b. IncreasingtheconcentrationofHOCH3.
Ph
Ph
c. ReplacingHOCH3withNaOCH3.
d. Changingthealkylhalidefromabromidetoaniodide.
e. Changingthealkylhalideto1-bromopropane.
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Chem.233–Chapter11-Pt.1ProblemSet
3. Foreachofthefollowingpairs,circletheonethatwillproceedfasterbyanSN2reactionmechanism.
F
vs
Br
Br
vs
Br
vs
Cl
Cl
Br + NaSCH 3
Br + HSCH 3
vs
Br + NaF
polar protic solvent
vs
Br + NaF
vs
Br + NaI
polar protic solvent
Br + NaI
polar aprotic solvent
Cl
polar aprotic solvent
Cl
vs
+ NaOH
polar aprotic solvent
+ NaSCH 3
polar aprotic solvent
Br + KI (high conc)
Br + KI (low conc)
vs
4. Foreachofthefollowingpairs,circletheonethatwillproceedfasterbyanSN1reactionmechanism.
vs
Br
Br
Br
Br
vs
vs
Cl
I
I
+
NH 3
vs
+
HOEt
(Solvent)
vs
Br
+
Cl
OH
(low conc)
I
+
NH 2
+
Br
vs
+
Cl
HOEt (1 equiv)
THF (solvent)
OH
(high conc)
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Chem.233–Chapter11-Pt.1ProblemSet
5. Explainwhythetworeactionsbelowprovideconstitutionallydifferentproducts.
NaOCH 3
OCH3
Br
HOCH 3
H 3CO
6. Assumingeachreactionbelowundergoesnucleophilicsubstation,predictthemechanism(SN1or
SN2)anddrawthemajorproduct.Includestereochemistrywhereappropriate.
Br
NaOH
Br
NaOH
Acetone
Br
NaCN
I
DMSO
NH 3
Cl
Br
NaSCH 3
DMF
Br
I
HO
OCH3
DMSO
I
HOCH 3
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Chem.233–Chapter11-Pt.1ProblemSet
Br
HSEt
DMSO
I
HOCH 3
I
OH
H
H 2O
Br
Br
Br
H 2O
HO
OCH3
Br
DMSO
7. ThecompoundbelowcanundergoanintramolecularnucleophilicsubstitutionviaanSN2
mechanism.Drawtheproductandthemechanismbywhichitisformed.
N
H
DMF
Cl
8. Explainwhythereactionbelowdoesnotprovideanyproductsfromnucleophilicsubstation.
+
Br
No Substitution Reaction
Na O
(NaOt-Bu)
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Chem.233–Chapter11-Pt.1ProblemSet
9. Predicttheproduct(s),withcorrectstereochemistryforeachofthefollowingsubstitutionreactions
involvinganalcoholstartingmaterial.
OH
(a)
OH
(b)
(c)
(d)
OH
1. TsCl
Pyr
2. NaBr
HBr
HI
HBr
OH
(e)
OH
(f)
OH
1. TsCl
Pyr
2. NaBr
NaI
THF
10. Showthecompleteelectronpushingmechanismforthereactioninquestion9a.
11. Showthecompleteelectronpushingmechanismforthereactioninquestion9d.
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