Exam
2: Whatwould have been,..
The following is a take home practice exam. When you are ready, set a timer for lhour and 15 minutes. You can check you answers against the answer key. Answers
will be ranked as easy (x), medium [**), and hard (***). Have fun!
1". Show the curved arows illustrating the following reactions. Make sure to show all
bond breaking and bond forming events (10 points).*
N
-t/-.
- cf
ill
ill
sN2
___>
+ @6:p
I
+Br
?
\
-^\ \
o
H--;-Br
.------->
'"Xi,€
@s'--
A
2, When 3-hexene is treated to Brrfollowed by NaNHr, an alkene is formed. However,
when cyclohexene is treated to the same conditions, a cyclohexadiene is formed. Explain
this difference? (9 points)**
_/
/-\
Br2 then
NaNH2
/
,/-
\-
Br2 then NaNH2
Ot
*
rY\
or€- s{^bta-
\s u-"'s\^LtL
3. Show the products or reagents for the following reactions. Make
stereochemistry when appropriate. (4 points each,2qpoints). **
a,,r
" \__
sure to address
F
OH
H2S04
H2o-
--D
MeMgBr
+5
)- aorug"6 or
lu:
aSStrrcr-S
-.>
t.,oot-
Vt^rlows
^ \ F_oH
/
cro3, H2so4
L
tsc,
Hzo
OsOaiNaHSO3
1+1:'o{-t
r _--r::'o$
LIt
Na/NH3
e.
---+
, r /-
-/
ilE
6r
f.
Brz
-->
llv'P
S. A trans double bond can be converted to a cis double bond by treatment of a
peroxyacid followed by treatment with triphenylphosphine. Explain the stereochemical
(10 points)***
butcome of this prorrrr, using mechanisms throughout the second step
ll
il
t. nAoon
+ Ph3PO
z.
\,{-
PPh3
&r{
Hlcn,
t
u/\
'!r -,,,
,
6un OI
PPh3
lic.,bH
?(
"il>
r"l
J
,
e?l.t
+u*
;W.
t-
4. Show the mechanisms of the following reactions, using curved arrows to illustrate
your reactions. (16 points, 8 points each)**
a.
--rvrfoezv
""o'- O
Oa^l,t)
OH
.t
so**
\
ffi*o=u
T'^Xt'.,^=)
C
M
q3
bos<
'
'
V
*h*'
,?
b.
rm"'
WNH,
H2S04
------------t>
J
cG'
A,@.v
-+ (-f
\,4/
t
9t%
g,Ji
-2
\./
-\{"-O
.I+
\r
+f\,t+-H
dl-,/.
(9, oso.H
6. The following syntheses can be carried out in 3 or fewer steps. Show a synthesis.
you use more then 3 steps, it is ok). (7 points each,2l points)**
----->
.--...>
a.
l*
N
fl,rP="ua
f*
Bil:j
--> nna+J
Lq
b.
I
^=*rO{/
o.oi q-llorr
,->
t
I
t
Pcc-*
)rucS
fu..f/tl'
c.
HB5
lwT-
I
b Lfu'
GL;
(If
7. Show a synthesis of hexane using methanol (H3COH) as your only carbon-based
stating materials. (10 poinls;*xx
l-{"cort
HrCotl
HFo
PBq
ffrc- B r
-+
6c.>e
?cc
->
+UC:ePl=
u
Jlt
e6
_ PPhs
w
:>"
H*:(H.
lr t.,
.H\
bi
^8.
^bB"
t*
Btt.-^,-g.
Q.,<
6r
\*.
Ov*- op\ion,
*""1 ,*\"{a*$
Lio
.^L;
CnT
-a?