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Chemistry233Chapter11ProblemSet–Pt.2(EliminationReactions)
1. TheexamplebelowwasgivenontheCh.9ProblemSet.Givenwhatyounowknow,whatproduct(s)
wouldyouexpecttoisolatefromthisreaction?
2. SpecifyhoweachofthefollowingwouldaffecttherateofanE2reaction.
a. IncreasechangingthebasefromNaOCH3toNaNH2.
b. Increasingtheconcentrationofbase.
c. Decreasingtheconcentrationofalkylhalide.
d. Changingthealkyhalidefrom2-bromo-2-ethylpentaneto2-bromopentane.
e. Changingthealkylhalidefrom2-bromopentaneto2-iodopentane.
3. SpecifyhoweachofthefollowingwouldaffecttherateofanE1reaction.
a. ChangingthebasefromNaOHtoH2O.
b. Decreasingtheconcentrationofbase.
c. Changingthesolventfromacetonetomethanol.
d. Changingthealkyhalidefrom2-bromo-2-ethylpentaneto2-bromopentane.4. Predicttheproduct(s)foreachoftheE2eliminationreactionsbelow.Identifythemajorproductfor
each.
Br+ ONa
(NaOt-Bu)
No Substitution Reaction
Br
Ph
Cl
Br
BrO
KOHHeat
NaOCH3
Heat
HeatO
a.
b.
c.
d.
BulkybasegivestheHofmannElimination productHRnfl 8tBu
rtGbrE2 Rate KCRX Base
Trate Nolte is a strongerbasethan 8dBT rate
to rateBryEt Brf rate Ezra letwithsubstitution 30Br 1 20Br
T rate TbetterLGEl Rate k Rx
Nocharge
No change
T rate Tpoleraprotic C polarProtic
Irate El rate with substitution
YT Zaitsev
Rotateso 49 Hectare 4 pf antiperiplosar
p No Rtn No BH
HofmannProduct
Answer Key
Chem.233–Chapter11-Pt.2ProblemSet
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5. Showthecompleteelectronpushingmechanismforthereactioninquestion4parta.
6. Predicttheproduct(s)foreachoftheE1eliminationreactionsbelow.Identifythemajorproductforeach.
7. Showthecompleteelectronpushingmechanismforthereactioninquestion6partc.
8. Foreachreactionbelow,predicttheE2eliminationproductwithcorrectalkenestereochemistrywhereappropriate.Also,drawthereactive(anti-periplanar)conformation.
9. Thecompoundbelowcanundergotwosuccessiveeliminationreactionsuponheating.Drawtheproductofthereaction.
Br
I
Br
H2OHeat
CH3OHHeat
CH3OHHeat
a.
b.
c.
a.
b.
Cl
PhNaOEtHeat
IEt
NaNH2Heat
PhCl
ClNaNH2DMF
YI t Ho t Bro2
my
Tu
E
ph pht b Phat t lhotoats
t B
o i Him
µqg ph zt8k Ph
Chem.233–Chapter11-Pt.2ProblemSet
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10. Circletheoneineachofthefollowingpairsthatwouldbeexpectedtogiveahigheryieldofeliminationoversubstitution.
11. Synthesis:Proposeasynthesisforeachofthefollowingstartingwith2-bromobutane.
a. 2-butene
b. 2-butyne
c. 2-butanold. butane
12. Rankthefollowingfromfastest(1)toslowest(4)E2elimination.
II + NaOH+ NaOH
Cl + KO Cl + KO
Br+ CH3O
Br+ CH3O
Low T High T
vs
vs
vs
a.
b.
c.
Br BrBr Br
zo faster E2Slower Snz Vs 10
Bulky base Cer onlydo elimination
High T favorselimination
Br or other small base1 a
or other baseF NENE See Q9Br nao 8 NIH1
Br N t1
A BC D
sina.inB H access reactiveconformation
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