Exam 2 Spring 2014
Name_______________________________________________ Room ____________
Student ID__________________________________________
Circle One
11:15 AM Class
Seat Number________
12:20 PM Class
The exam consists of 10 questions on a total of 12 pages, including periodic table.
1. _____/10
2. _____/10
3. _____/10
4. _____/10
5. _____/10
6. _____/10
7. _____/10
8. _____/10
9. _____/8
10. _____/12
Regrading: All requests for regrades must be submitted in writing within 48 hours of the
return of the exam. You must explicitly state what has been misgraded and why it is an
error. The entire exam will be regraded, which could result in points being added or
deducted overall.
1
1. (10 points) Draw a mechanism for each of the following reactions.
a) (4 points)
b) (3 points)
c) (3 points)
2
2. (10 points)
a) (6 points) Draw all of the stereoisomers of the following compound.
b) (4 points) Using Newman projections draw the highest energy conformation of the
compound illustrated below. Only consider conformations that rotate the indicated bond.
3
3. (10 points)
a) (6 poitns) Please identify if each of the following compounds are “chiral”, “achiral” or
“achiral and meso”. If the compound contains chirality centers, please indicate R or S for each
center.
b) (4 points) Determine the relationship between the followings pairs of compounds. Write
“same,” “constitutional isomers,” “enantiomers,” or “diastereomers.”
4
4. (10 points)
a) (5 points) The difference between the axial and equatorial conformations of compound A is
-5.4 kJ/mol. Why is this different than the free energy difference between axial and equatorial
conformations of methylcyclohexane, which is -7.6 kJ/mol? Please support your answer with
figures and text.
b) (5 points) When compound A is dissolved in aqueous HCl, the difference between the axial
and equatorial conformations of compound A is now very similar to that of
methylcyclohexane, why? Please support your answer with figures and text.
5
5. (10 points)
a) (3 points) Draw the lowest energy conformation of 2-methylbutane.
projection to illustrate your answer.
b) (3 points) Draw the highest energy conformation of 2-methylbutane.
projection to illustrate your answer.
Use a Newman
Use a Newman
c) (4 points) Using the values provided at the end of the exam, what is the energy difference
between these two conformations.
6
6. (10 points) Consider the following SN1 reaction and answer the following questions.
a) (2 points) What is the rate equation of this reaction?
b) (2 points) Would the reaction occur at a faster rate if the concentration of NaBr was doubled?
Provide a brief explanation.
b) (6 points) Draw a reaction coordinate energy diagram for the above process. (You may
assume the reaction is exergonic) Clearly identify all intermediates and transition states.
7
7. (10 points)
For the following substitution reactions, fill in the blank. (2 points each)
a)
OH
HCl
b)
include a proper
solvent
Cl
SH
c)
NaCN
DMSO
(R)-2-iodoheptane
d)
Br
EtOH
e)
OTs
OH
8
8. (10 points)
a) (6 points) Predict the major product(s) in each elimination reaction.
b) (4 points) Under each potential product of this E2 elimination, write “major product,” “minor
product,” or “not formed.”
9
9. (8 points) Draw the products and provide mechanisms for these reactions.
10
10. (12 points) For each of the reactions below, indicate the major mechanism by which it
proceeds as either E1, E2, SN1, SN2, or a mixture of these mechanisms. Then draw the major
product of each reaction. (Partial credit will be given for a major product consistent with the
mechanism selected, even if the selected mechanism is incorrect. If the major product given is
inconsistent with the selected mechanism, then it is wrong.)
11
PERIODIC TABLE OF THE ELEMENTS
1
H
1.008
3
Li
6.941
11
Na
22.99
19
K
39.10
37
Rb
85.47
55
Cs
132.9
87
Fr
(223)
4
Be
9.012
12
Mg
24.31
20
Ca
40.08
38
Sr
87.62
56
Ba
137.3
88
Ra
(226)
1
Atomic Number
H
Symbol
1.008 Atomic Weight
5
B
10.81
13
Al
26.98
21
22
23
24
25
26
27
28
29
30
31
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
44.96 47.88 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.39 69.72
39
40
41
42
43
44
45
46
47
48
49
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
88.91 91.22 92.91 95.94 (98) 101.1 102.9 106.4 107.9 112.4 114.8
57
72
73
74
75
76
77
78
79
80
81
La
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
138.9 178.5 180.9 183.9 186.2 190.2 192.2 195.1 197.0 200.6 204.4
89
Ac
(227)
6
C
12.01
14
Si
28.09
32
Ge
72.61
50
Sn
118.7
82
Pb
207.2
7
N
14.01
15
P
30.97
33
As
74.92
51
Sb
121.8
83
Bi
209.0
8
O
16.00
16
S
32.07
34
Se
78.96
52
Te
127.6
84
Po
(209)
58
Ce
140.1
90
Th
232.0
69
Tm
168.9
101
Md
70
Yb
173.0
102
No
71
Lu
175.0
103
Lr
59
Pr
140.9
91
Pa
(231)
60
Nd
144.2
92
U
238.0
61
Pm
(145)
93
Np
62
Sm
150.4
94
Pu
63
Eu
152.0
95
Am
64
Gd
157.3
96
Cm
65
Tb
158.9
97
Bk
66
Dy
162.5
98
Cf
67
Ho
164.9
99
Es
68
Er
167.3
100
Fm
9
F
19.00
17
Cl
35.45
35
Br
79.90
53
I
126.9
85
At
(210)
2
He
4.003
10
Ne
20.18
18
Ar
39.95
36
Kr
83.80
54
Xe
131.3
86
Rn
(222)
Conformational Energies:
H/H eclipsing
H/CH3 eclipsing
CH3/CH3 eclipsing
CH3/CH3 gauche
4 kJ/mol
6 kJ/mol
11 kJ/mol
3.8 kJ/mol
Scratch work:
12