Exam 2 Spring 2008

Chemistry2623- Exam2
Feb. 28, 2008 FormB
Name:
- - - - ---
MULTIPLECHOICE(63 pt). Write the letter (number) corresponding to the best answer for questions
1-21 on your par score form.
d) B <A <C 0 C < A < B
c.
c) C <B <A b) A <C <B
1. Rank the following compounds in order of increasing reactivity toward electrophilic
aromatic substitution.
2. Which ofthe following compounds has an infrared spectrum that includes C-H stretches
around 2700-2800 em-I and a sharp strong peak near 1700 em-I & a NMR signal at 9-10
ppm? C- 0 . 01-
r\ ) <( ( ) O-CH
3
H
3. Show the product when 3-pentanone is treated with LiAID
4
then H
2
0 workup.
b)
---------.CH----
I
OH
G
--------.co----
I
OH
c)
--------.co----
I
00

. II
o
G
.Rank the following compounds in order of increasing acidity [less acidic < most acidic]?
;;;00.-
o 0 1 A
(00H \ J/") '})
1 2
eY
oH

a) 1 < 2 < 3 < 4 b) 2 < 4 < 1 < 3 c) 3 < 4 < 1 < 2 d) 4, < 1 < 3 < 2
J
Bf2
FeBr3
... or!

a) 2-bromo-6-methylphenol and 4-bromo-2-methylphenol fb.Y
3-bromo-2-methylphenol and 5-bromo-2-methylphenol
c) .-bromo-2-methylphenol and 4-bromo-2-methylphenol '»-bromo-2-meth
Y
I
P
henol
J .
6. Which of the following statements the carbonyl group (C=O) is false?
5. Predict the major product(s of the following reaction.
0\\ 0 OH
V ttl? 6r
CH3
a) It is planar with bond angles of near 120° J
b) Carbon uses an Sp2 and p orbital to form the carbonyl sigma and pi bonds respectively
(C) It readily undergoes attack by electrophiles at the carbonyl carbo!} atom
)r) Like the C=C bond it can undergo addition of H
2
to its pi bond V
---40vethe expected product ofthe following reaction. [Me methyl]

HO" 2) H
2
0 ,neutral i:ze
'\ OVlt)
8) Which of the following compounds gives a primary alcohol upon reaction with
phenylmagnesium bromide? Assume the usual acid workup.
'A=c=o
9. Which of the following hydrogens (a-d) on n-propylbenzene would be most reactive towards
free radical substitution using NBS (N-bromosuccinimide)?
a b';
-, <}=CH2-CH2-CH3'11 d
J
- - -- --- - - -,- , - -------
6 What is the product ofthe following reaction with excess LiAlH.?
0

o

A.
o

c.
OH


1) ether
---..
2) Hi,0+
1) ether
---..
2) Hi,0+
12. Rank the following (A, B, C) interms of acid strength (strongest> weakest):
.....
a) 1> 2 > 3 a1> 3 > 2 c) 2 > 3 > 1

). the product ofthe following reaction? [Et ethyl]

U CI
3)
d) 3 > 1 > 2
0 OH

o f:) OH

J
on the pK
a
values given, which of the following statements regarding alanine is
-- ,
H,NJyOH H,vlyO-
o 0 0"\)\\
pKa 2.3 pKa 9.7

is a stronger acid than propanoic acid b) The isoelectric point of alanine is 6.0
c t the isoelectric point, alanine exists primarily as the dipolar zwitterion ion
. At pH 12, alanine is uncharged
15. Which compound reacts with both and H
2IPd-C
to produce the same product?
o
a) II
3C-C-CH2-CH3
o
b) II
H
3C-C-CH=CH2
d) none of these
d) ( )-CH,oCH,-OH _
AlwVlOL
17. Why is the nitro group a meta director?
A. Because it is sterically very large
B. Because it adds electron density to the meta position, thus activating it
C. Because it stabilizes the intermediate cation \
®Because it removes more electron density from the ortho and para positions than thcV\eta
position, thus deactivating the meta position less 9J4l'\-l
01---
18. Which of the following organometallic compounds has the least amount of nucleophilic character
(i.e., less Ir charge) and is not as reactiveas the others? e-Ylcn
c) H-C==CNa
_. . . . - - _ . _--
19. The preferred atom (a-d) for attack by the dimethyl organocuprate nucleophile on the
carbonyl compound below is
+
C)
b) B >A>C @ C> A> B d)B >C> A @ > B > A a) A >B >C
20. The expected order of boiling points (highest to lowest) of the following molecules , all of
similar molecular weight (58-60 g/mol), is:
[end ofmultiple choice; write remaining answers directly on the test booklet]
I H-o-0CH3
23. (5 pt) Explain why the methoxy group activates the first benz 1ing (1) towards
electrophilic substitution (e.g., attack by Brl at the p-position, but when attached to p-
position of benzoicacid (II) makes it a weaker acid. You 'may show intermediates or
resonance forms if you wish. 1YJe. meTl10 parnvotts, f11e- nst
\? eVI l eVI V1 Vf ra cc 1l1
t
- 0(;/3
10 P 11111)9 e ' ; 1 fA \IV1).1 f\4l n
t V\ hq \IvVul e, 5;; ewyyJ ont
;JutA; n T M f Y 1 1 ~ n - ~ (<-- ()[IlHY,2
r 1)1t t r rOVl ~ I fA w) f,1V1d
1 Vlt V1Q.
........ _ , .... , ..... r r • r ~
24. (4 pt) Draw two resonance forms (one showing substituent interaction) for the a- cation
formed upon ortho bromination of C
6HsOH.
Start by utilizing arrow shown.
o
\}-O-H .
\, Br+
H
A=
2. CO
2
,
then acid
1. Mg
25. (21 pt) What are the major organic products [A-H] of the following reactions?
o
"
aC' OH j
Br
¢
CHO
D =
E=
Na+mI
2
-
H
3C-C==C-H
.. G
H=
H
30
+
------l.. ~ H
0\1
I
I 1 ~ C - C - C H
\
c~ \ l C H ~
- - ----- -- - ---- -- - - -
-
, . I
o
26. (6 pt) a) Both carboxylic acids & phenols are stronger acids than alcohols. Show at least one
other resonance form for the conjugate bases of benzoic acid & phenol below, that helps
(XPl)ilierr(at:bi(;<oal:OXid<on,)-. 0- _
b) Comparing resonance structures drawn, suggest why benzoic acid (pKa = 5) is a
stronger acid than phenol (pKa = 9). 1/\ . \- 0 YJ1 Ves.
BeV1 2-D Iv iI1 CtO 10 VI s1v1wlgev aCId vera U, I I I 0 e
0t (,l111l \leLl VlO pl1 f\10l ){1fd'vvJo t!?i IAqa Vt1<;&.
t Q, eV1H10 Vl citl hAl?
27. (7 pt) Synthesize the following compound from cyclohexanol, and any other needed organic or
inorganic reagents (show reactions required in the multistep buildup of this molecule).
28. (6 pt) Show the mechanism (3 or 4 steps) for the reaction shown (use arrows to show
movement of nucleophiles to electrophiles & flow of electrons & draw intermediates)
r
0-
//5 ether H30+ o-,H
\\ j + 2 H
3C-Li
.... . \ j ,-CH
3
I H
3C

J H- HzL 1;\
/ c f - Cth ') II
{
29. (4) What is the stereochemistry of the 2-butanol product obtained in the reaction below? \----...
o l )NaBH, '"
'} • • I I r It
What procedural modification (method) would you use to obtain pure R-2-butanol?
\!l 0e., G- PkSC fA {# OYl t Of veaqantc..
" ...... r I , • I 1"'- " ii -I - - . - - -
, """,-:-;-- --- - -