Prep 101 Booklet (2013) Part 7
Exam Booklet
OPrep101
(b)Nirration
P*b *{,''/
UT-U/ S"ZO|
d'rt
/
a,m^"a.h
,,§ o" b*,< '8' "-o-,Ë,--t 'o', Ùl) y'." Ë*Ë_-1 ., t l-1. I 1 -.-.p., '1,
'
,..
,/rffi HÈh'-Wa
tr0,
,.,
^*:1,il,",",,,,,ffi
A*;Ï;chbrides,-"W,
aluminum chloride
ct
*Jâ*À-c, \
CI
,,\
+
ofrî .#,1,H
-t--..--l
) ët
a-+Arcr4ebctrophile
,v
Atct3
+
Alcla-
_,:-,( \)
+Hcr +Arcr3
, «@ __-s : Hrsq
AtnV'{
"
tr
will be posted at www.prep10l.com/solutions
139
I
@Prep101
Chem212 Exam Booklet
This reaction has several limitations: (1)
The reaction does not work when the aromatic ring is substituled wilh slrong/y electron withdrawing groups (EWG) or amino groups
r]\
o?ry
ct
EWG
ct
I no reaction
ô
AICt3
.olffi'ffi-ffi'ilk*ffi no substitution product
chloride generates a carbocêtion (the electrophale),
the cârbon skeleton is subject
to carbocataon rearragements yielding
undesired products
ry- o-r
-.--.---1....-c, Atct3
maior product
,-\-.-L., +
Arcb
+
-^-.)tr't
-
minor
producl 1.2-hydride shifr
o,",.
,^.-iLx
ercr.
elec{rophile thât l€ads to
(3)
rr ii"JTË.^r rhe aromatic
arkvrarion reacrion is difficurt to stop
observed
o ,*1
c
"1 à-
aft",
onu.ro,tl.,ili.
^iu,3
", S*)ro'fl ,
À
maior
ir"ird&
product
a)?
«al
Aii*',liif:ii;'l'
+ é-,,*rrWu#
t
4)
The reaction does not work fôr aryt hatides or vinylic h€lides
.
âia. '
,J,:,'^'Ü Ot-* o'nÀ 4-*?.mffi L )*;b&';;tüo O :- n,alc ti*s. i,
-
.t"p sârutions
wil
be posted
,
.t
/
. 't.:','': b*llfu /k ',"t o'.Y à'^.ln ,:!
w*w.pref,-ro,.r:sff"itff"c
.t40
/À
lr^/r*-/r"@Prep101
Chem212 Exam Booklet
fd) Aromatic acylations
.
Aromatic rings are acyrated lyhen rÇected,with açvr chrorides and âluminum chroride
1
A,.t
ÿe
Wa,,
^ .t^t,,";l'/"_Lq).
YÙ1 hotr
,i"1",
\-
fu 4Yû'4
w
__L +
:
A,cr4
erecrroph,re
\_/cr
' u
R-c-o, ^-"-Y.
W Itl,
-t3 -ru* --to -*.) catron
.
'r"ula
O ;#
ft1o'"a
,-*^" \/
-tJ
*(J
«J/ AC13
oilE /pra dir€clirg
-]= IJ
r,.
cucl,
I
si.bslilærls Éanb|De
€ar
g|atlEr
i-2 lr 'l
Bi. l' --------------> ll
FeBrl
W
ncla û..tor
E,r2 I
\rlr,
8r
norÈ
FeBr,
+ffib# i6
To,
..\-
Br
-
No,
-L
?u,* \À, Br
tÈ,{ÿElidi!g, so it
üÉat3
,/tu-.{"q we fuYLCX'L'V )^*"1"'%Us
t^/tIy
-
Solutions will be posted at www.prep101.com/solutions
145
OPreplOl
Chem212 Exam Booklet
7.4.5 Reactions of aromatic compounds Alkylbenzene side chains can be oxidized to carboxylic acids using KMnOa, 'OH, HrO, heat.
il
fv\\'/ -l \-[) a\-\
KMnoo, oH-.
Note: The atkyr side chain must
this reaction to
.
"on,"in
occur
H,o
/.\"-"*'
{ilfrlIà})
0{d,4!',
conjugated group, or atcohor for
--/
Alkylbenzene sidechains can be brominated at the benzylic position with NBS
o
o
rY"* \/v - d"-,,
rohr ra\a^Br ;Ëi.' \)
b
Benzÿ
F -\
ÇN-H
bromide
\
(lr-bromotoluene) NBS
(64%)
General Mechanism of Benzylic Halogenation: eâ.hr,nablio,| Step
I
p$nirêÉ,
i\ P{oridei.
E. ryf
zx.
or
lght aal,'a hrlogaat riola.uhe lo de.Ia into r.d*:da. haat. or
ClriaAD,4abn Sr4'
.?
H
C.H!
trar-C-H l'H
--. x'. _-
,H
ctt-l.-Ci
. H- x
H
Bdlry{ rdcaa
Ândoggr a
rrlcd.bdir.ct!. b
ben:ÿlic aadicd rnd
rÿtÈ Brolpn rh!!, tomlE -
a molacule ot ül§
Slfp J -H
QH.-C:/ tH - X-:X
....
Ee,rtÿ|.ldlarl
Wooen haride. H
c*r1-Ü-x
r
x,
ü Eellrtl hald.
Th. benzÿlh rrdical lfICIE ÿ.th s h.lo{si nolccuta to iorm làc bentylic halide prodllct rrü r hâlogei r tic.l hat Fopâglt a t tô.iain
CrrlDlûrr,.Etton
w1
anO
c.n.cH,f'd'rx qn,cnii :cu"qn, .--
cÉH5cH.-x
I
CÉH5cH!-cHrc6H,
Vrrixtg ndlcll coarpli.g reacllorrs laa,nlnate rh. clu:n.
r
Solutions will be posted at www.prep101.com/solutlons
146
I I
OPrep101
o
Chem212 Exam Booklet
Benzene can be partjally hydrogenated via the Birch Reduction: Na lq. NH}
EIOH
Mechanism:
OfÀtA..-,O.**] Bemene
Benzeæ radical anion
l,*
f,rî 'tr- l L)'/-,{).*"."1 C'yclotnxadiny' radical
I*..
Cycloheradienyl anion
'1,4{yclohexadiene
fu/ UW ?+
Solutions will be posted at www.prep101.com/solutions
^pl
147
OPreP101
7.4-G Nucleophilic Aromatic Substitution
.
When aromatic halides are substituted with electron withdrawi
para- positions they can react with nucleophiles. The reaction takes place through an
NO, Carbanion (Meisenheimer intermediate)
Resonance of the l\ileisenheimer I ntermediate:
HO
Ct
HO
Ct
HO
HO
Ct
CI
,(')
"'.-
\\lf
4 k,zfu* 4"§ffiï*ffi, î'-? ."-/, n, 4 "*O A ? TbT
_N'oo ' -ci.
t
I
I
Solutions will be posted at www.prepl01.com/solutions
148
OPrep101
7.5 1.
Chem212 Exam Booklet
Practice Problems ldentify the aromatic compounds. For lhose that are not aromatic, specify why.
qooü lr.É' fu'[,u, NN
H
ôô
æ
üd^'
o^k;lw ,h'
Draw a curved anow reaction mechanism to account for the product formed in the forowing reaction. Be sure to incrude initiar erectrophire generation and
a[ significant intermediate
resonance forms. BT
Br
CI,
ô
ct-ct
FeCll
FeCt3
-t
L) T ct
rc;Àffe{-,,,?,,=
Kq-Ç/ Br\
'E"e\t',, d"
Solutions will be posted at www.prep1Ol.com/sotutions
149
OPrepLol 3.
chem212 Exam Booklet
Draw two additional resonance structures of nitrobenzene that both illustrate how the nitro group affects the reactivity of the aromatic system towards electrophiles.
oo'@.,,o
ê
I
-'::
ttt \
4.
/'?
of resonance contrlbutors in the nitration a)Draw the struclure of the 2 most significant toluene. in the nitration reaction' b) Show the formation of the etectrophilic species
Solutions will be posted at www'prep101'com/solutions
150
Chem212 Exam Booklet
5. Propose a mechanism for the nilration of bromobenzene to give parabromonitrobenzene.
o
,-\ ( +:g tttN
O"#;^C'"
/
\
l^
l,il ^o
u-ù
It
0
\[
{u'--»" [ios-' lN\", tl
.Hro
'
Provide the major product/starting materiarÿreagents for each of lhe foflowing .eactions a)
tto
c) hot
c(cHr)3 Bt:
b)
/:\ 1l ,^ cr {( )}-o-i-{( )Frt È4 \=7
i
onc sqtri\irlcnt)
[c
1
Solutions will be posted at www.prep10l.com/solutions
152
OPrep101
(b)Nirration
P*b *{,''/
UT-U/ S"ZO|
d'rt
/
a,m^"a.h
,,§ o" b*,< '8' "-o-,Ë,--t 'o', Ùl) y'." Ë*Ë_-1 ., t l-1. I 1 -.-.p., '1,
'
,..
,/rffi HÈh'-Wa
tr0,
,.,
^*:1,il,",",,,,,ffi
A*;Ï;chbrides,-"W,
aluminum chloride
ct
*Jâ*À-c, \
CI
,,\
+
ofrî .#,1,H
-t--..--l
) ët
a-+Arcr4ebctrophile
,v
Atct3
+
Alcla-
_,:-,( \)
+Hcr +Arcr3
, «@ __-s : Hrsq
AtnV'{
"
tr
will be posted at www.prep10l.com/solutions
139
I
@Prep101
Chem212 Exam Booklet
This reaction has several limitations: (1)
The reaction does not work when the aromatic ring is substituled wilh slrong/y electron withdrawing groups (EWG) or amino groups
r]\
o?ry
ct
EWG
ct
I no reaction
ô
AICt3
.olffi'ffi-ffi'ilk*ffi no substitution product
chloride generates a carbocêtion (the electrophale),
the cârbon skeleton is subject
to carbocataon rearragements yielding
undesired products
ry- o-r
-.--.---1....-c, Atct3
maior product
,-\-.-L., +
Arcb
+
-^-.)tr't
-
minor
producl 1.2-hydride shifr
o,",.
,^.-iLx
ercr.
elec{rophile thât l€ads to
(3)
rr ii"JTË.^r rhe aromatic
arkvrarion reacrion is difficurt to stop
observed
o ,*1
c
"1 à-
aft",
onu.ro,tl.,ili.
^iu,3
", S*)ro'fl ,
À
maior
ir"ird&
product
a)?
«al
Aii*',liif:ii;'l'
+ é-,,*rrWu#
t
4)
The reaction does not work fôr aryt hatides or vinylic h€lides
.
âia. '
,J,:,'^'Ü Ot-* o'nÀ 4-*?.mffi L )*;b&';;tüo O :- n,alc ti*s. i,
-
.t"p sârutions
wil
be posted
,
.t
/
. 't.:','': b*llfu /k ',"t o'.Y à'^.ln ,:!
w*w.pref,-ro,.r:sff"itff"c
.t40
/À
lr^/r*-/r"@Prep101
Chem212 Exam Booklet
fd) Aromatic acylations
.
Aromatic rings are acyrated lyhen rÇected,with açvr chrorides and âluminum chroride
1
A,.t
ÿe
Wa,,
^ .t^t,,";l'/"_Lq).
YÙ1 hotr
,i"1",
\-
fu 4Yû'4
w
__L +
:
A,cr4
erecrroph,re
\_/cr
' u
R-c-o, ^-"-Y.
W Itl,
-t3 -ru* --to -*.) catron
.
'r"ula
O ;#
ft1o'"a
,-*^" \/
-tJ
*(J
«J/ AC13
oilE /pra dir€clirg
-]= IJ
r,.
cucl,
I
si.bslilærls Éanb|De
€ar
g|atlEr
i-2 lr 'l
Bi. l' --------------> ll
FeBrl
W
ncla û..tor
E,r2 I
\rlr,
8r
norÈ
FeBr,
+ffib# i6
To,
..\-
Br
-
No,
-L
?u,* \À, Br
tÈ,{ÿElidi!g, so it
üÉat3
,/tu-.{"q we fuYLCX'L'V )^*"1"'%Us
t^/tIy
-
Solutions will be posted at www.prep101.com/solutions
145
OPreplOl
Chem212 Exam Booklet
7.4.5 Reactions of aromatic compounds Alkylbenzene side chains can be oxidized to carboxylic acids using KMnOa, 'OH, HrO, heat.
il
fv\\'/ -l \-[) a\-\
KMnoo, oH-.
Note: The atkyr side chain must
this reaction to
.
"on,"in
occur
H,o
/.\"-"*'
{ilfrlIà})
0{d,4!',
conjugated group, or atcohor for
--/
Alkylbenzene sidechains can be brominated at the benzylic position with NBS
o
o
rY"* \/v - d"-,,
rohr ra\a^Br ;Ëi.' \)
b
Benzÿ
F -\
ÇN-H
bromide
\
(lr-bromotoluene) NBS
(64%)
General Mechanism of Benzylic Halogenation: eâ.hr,nablio,| Step
I
p$nirêÉ,
i\ P{oridei.
E. ryf
zx.
or
lght aal,'a hrlogaat riola.uhe lo de.Ia into r.d*:da. haat. or
ClriaAD,4abn Sr4'
.?
H
C.H!
trar-C-H l'H
--. x'. _-
,H
ctt-l.-Ci
. H- x
H
Bdlry{ rdcaa
Ândoggr a
rrlcd.bdir.ct!. b
ben:ÿlic aadicd rnd
rÿtÈ Brolpn rh!!, tomlE -
a molacule ot ül§
Slfp J -H
QH.-C:/ tH - X-:X
....
Ee,rtÿ|.ldlarl
Wooen haride. H
c*r1-Ü-x
r
x,
ü Eellrtl hald.
Th. benzÿlh rrdical lfICIE ÿ.th s h.lo{si nolccuta to iorm làc bentylic halide prodllct rrü r hâlogei r tic.l hat Fopâglt a t tô.iain
CrrlDlûrr,.Etton
w1
anO
c.n.cH,f'd'rx qn,cnii :cu"qn, .--
cÉH5cH.-x
I
CÉH5cH!-cHrc6H,
Vrrixtg ndlcll coarpli.g reacllorrs laa,nlnate rh. clu:n.
r
Solutions will be posted at www.prep101.com/solutlons
146
I I
OPrep101
o
Chem212 Exam Booklet
Benzene can be partjally hydrogenated via the Birch Reduction: Na lq. NH}
EIOH
Mechanism:
OfÀtA..-,O.**] Bemene
Benzeæ radical anion
l,*
f,rî 'tr- l L)'/-,{).*"."1 C'yclotnxadiny' radical
I*..
Cycloheradienyl anion
'1,4{yclohexadiene
fu/ UW ?+
Solutions will be posted at www.prep101.com/solutions
^pl
147
OPreP101
7.4-G Nucleophilic Aromatic Substitution
.
When aromatic halides are substituted with electron withdrawi
para- positions they can react with nucleophiles. The reaction takes place through an
NO, Carbanion (Meisenheimer intermediate)
Resonance of the l\ileisenheimer I ntermediate:
HO
Ct
HO
Ct
HO
HO
Ct
CI
,(')
"'.-
\\lf
4 k,zfu* 4"§ffiï*ffi, î'-? ."-/, n, 4 "*O A ? TbT
_N'oo ' -ci.
t
I
I
Solutions will be posted at www.prepl01.com/solutions
148
OPrep101
7.5 1.
Chem212 Exam Booklet
Practice Problems ldentify the aromatic compounds. For lhose that are not aromatic, specify why.
qooü lr.É' fu'[,u, NN
H
ôô
æ
üd^'
o^k;lw ,h'
Draw a curved anow reaction mechanism to account for the product formed in the forowing reaction. Be sure to incrude initiar erectrophire generation and
a[ significant intermediate
resonance forms. BT
Br
CI,
ô
ct-ct
FeCll
FeCt3
-t
L) T ct
rc;Àffe{-,,,?,,=
Kq-Ç/ Br\
'E"e\t',, d"
Solutions will be posted at www.prep1Ol.com/sotutions
149
OPrepLol 3.
chem212 Exam Booklet
Draw two additional resonance structures of nitrobenzene that both illustrate how the nitro group affects the reactivity of the aromatic system towards electrophiles.
oo'@.,,o
ê
I
-'::
ttt \
4.
/'?
of resonance contrlbutors in the nitration a)Draw the struclure of the 2 most significant toluene. in the nitration reaction' b) Show the formation of the etectrophilic species
Solutions will be posted at www'prep101'com/solutions
150
Chem212 Exam Booklet
5. Propose a mechanism for the nilration of bromobenzene to give parabromonitrobenzene.
o
,-\ ( +:g tttN
O"#;^C'"
/
\
l^
l,il ^o
u-ù
It
0
\[
{u'--»" [ios-' lN\", tl
.Hro
'
Provide the major product/starting materiarÿreagents for each of lhe foflowing .eactions a)
tto
c) hot
c(cHr)3 Bt:
b)
/:\ 1l ,^ cr {( )}-o-i-{( )Frt È4 \=7
i
onc sqtri\irlcnt)
[c
1
Solutions will be posted at www.prep10l.com/solutions
152
