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Chemistry234Chapter16ProblemSet

ElectrophilicAromaticSubstitution1) Predicttheproductanddrawthemechanismforelectrophilegenerationforeachofthe

followingreactions.

2) ExplainwhyreactionofbenzenewithBr2/FeBr3resultsintheproductbromobenzneinsteadof5,6-dibromo-1,3-cyclohexadiene.

3) Predicttheproductanddrawtheactiveelectrophileforeachreactionshownbelow.

Cl2FeCl3

HNO3

H2SO4

SO3

H2SO4

(a)

(b)

(c)

AlCl3(a)

(b)

(c)

Cl

AlCl3

Cl

AlCl3

Cl

O

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4) ExplainwhyeachofthefollowingsubstratesdonotundergoFreidel-Craftsreactions.

5) Arrangethefollowingbenzenesubstituentsinorderofreactivityinelectrophilicaromaticsubstitutionreactions.

6) Predictthemajorproductswhenthefollowingbenzenederivativesaretreatedto

nitrationconditions(HNO3/H2SO4).

7) Writethefullelectronpushingmechanismforthenitrationoftoluene.

NH2 NO2 N(CH3)3 NH

Ph PhCl

Ph

O

PhN

PhHN

OPh

HN Ph

SPh O

O

O

Br

NH2Br

NO2Cl

a.

b.

c.

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8) Predicttheproduct(s)wheneachofthefollowingbenzenederivativesistreatedtochloroethaneandAlCl3.

Br

NH2

Cl

OHCl

Cl

OH

Br

a.

b.

c.

d.

SO3H

NO2Cl

Cl

Br

Br

e.

f.

g.

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9) Predicttheproduct(s)whenthefollowingbenzenederivativesaresubjectedtoelectrophilicchlorinationconditions(Cl2,FeCl3).

10) Predicttheproduct(s)foreachofthefollowingreactions.

OH

NO2

NO2

O OH

Br

SO3H

a.

b.

c.

d.

Br O

OCH3

O

H3CO

OCH3

HO

Br NO2

Cl2

FeCl3

HNO3

H2SO4

SO3

H2SO4

SO3

H2SO4

a.

b.

c.

d.

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11) Predicttheproductforeachbenzeneside-chainmodificationreactionshownbelow.

12) Proposeasynthesisforeachofthefollowingcompoundsstartingwithbenzene.

a.

b.

c.

d.

KMnO4

H2CrO4

NBSlight

NO2 H2Pd/C

e. NO2 SnHCl

f.Zn(Hg)HCl

O

g.N2H2HO-

O

a. COOH

COOH

NO2

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b. NH2

Cl

c.

Cl Br

NO2

d.NO2

Cl

O

e. COOH

ClBr

NO2

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DiazoniumIonReactions13) Writeoutthesyntheticsequencetopreparephenolandacetanilide(Ph-NHCOCH3)from

benzene.

f.

Cl NO2

O

g.Br

O2N

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14) Providesynthesesforeachofthefollowingcompounds,freeofotherisomers.Yourstartingmaterialshouldbebenzeneineachcase.

Br

OH

a.

I Clb.

BrF

Br

c.

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NucleophilicAromaticSubstitution15) Foreachreactionshownbelow,determineifthereactionis(a)electrophilicaromatic

substitution,(b)NucleophilicAromaticSubstitution:Addition-Elimination,or(c)NucleophilicAromaticSubstitution:BenzyneMechanism.

NC

d.

ClNaOH350 °C

ClNaNH2

NH3

ClNaNH2

NH3

H3C

Cl

NaOH

NO2

ClHNO3H2SO4

Br

NO2

NO2 NaOCH3

a.

b.

c.

d.

e.

f.

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16) Showthefullelectronpushingmechanismforreaction15c.

17) Showthefullelectronpushingmechanismforreaction15d.

18) Explainwhythereactionshownbelowdoesnotoccur.

19) Considerthereactionshownbelow.Theoretically,therearethreepossibleproducts.Draw

eachoftheseproducts.Inrealityonlyoneoftheseproductsisformed.Whichoneistheobservedproduct?

Cl

NO2O2N

NaOHHeat

OH

NO2O2N

Cl

NO2

OCH3Cl

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20) Showtwomethodstosynthesizethemoleculeshownbelowstartingwithbenzene.Onerouteshouldusediazoniumionchemistrywhiletheotherrouteshouldnot.

21) ShowthereactionofphenolwithNaOH.

22) ShowthereactionofbenzoicacidwithNaOH.

23) Isphenolorbenzoicacidastrongeracid?Explain.

24) ShowthereactionofanilinewithHCl.

NO2

OH

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25) Rankthecompoundsineachsetbelowinorderofincreasingacidity.

26) Ranktheanilinederivativesbelowinorderofincreasingbasicity.

ChallengeProblems27) Writeamechanismforthefollowingreaction.

NH2 OHO

OH

O

OH

Br

(a)

OH(b)

OHNO2 OH OHO2N

NH2

O2N

NH2

O

NH2

O

NH2

H H

O

HCl

Cl

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28) PredictthemajorproductforthereactionofpyrrolewithBr2,FeBr3.Hint:useresonanceanalysisoftheintermediatetodeterminethepreferredregioselectivityofthereaction.

29) Showtheelectronpushingmechanismforthereactionshownbelow.

30) Substitutedpyridinesareknowntoundergonucleophilicaromaticsubstitutionviaanadditioneliminationmechanism.Predicttheproductandshowthemechanismforthereactionshownbelow.

HN Br2

FeBr3

OH

SO2NO2

NaHO

SO2

NO2

N Br

OH


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