CHE 230 - Organic Chemistry
Exam 3, April 3, 2002
Name
Student ID No.
Before you begin this exam: First: You are allowed to have a simple model set at your seat.
Please put away all other materials. Second: Place your student identification on your desk. A
proctor will come around to check everyone’s ID. Third: Read through the entire exam. Your
goal, as always, is to score as many points as possible. Do not waste time on problems that you
can’t do if there are others that look easy. Fourth: It is critically important that your answers be
written in a clear, unambiguous manner. Answers in which your intentions are unclear will not
receive credit. Fifth: READ THE INSTRUCTIONS FOR EACH PROBLEM. You have
until 9:50 to complete this exam. There will be no extensions, so budget your time carefully.
If you wish to have your exam score posted beside your student ID number in the glass case (1st
floor, CP Building, behind CP-139) with the exam key, place an ‘X’ in this space
. If
you do not mark this space, your exam score will not be posted.
Problem
Points
1.
15
2.
12
3.
12
4.
20
5.
5
6.
7
7.
15
8.
5
9.
6
10.
3
Total
100
Score
1
1.
(15 points) Match the energy profile diagrams (A-D) to the reactions below. You can
use one diagram more than once.
a) SN1 reaction with Keq > 1
b) E2 reaction with Keq < 1
c) E1 reaction with Keq > 1
d) A rapid E2 reaction with Keq> 1
e) A slow SN2 reaction
G
G
A
Progress
G
B
Progress
G
D
C
Progress
Progress
2
2.
(12 points) Match the energy profile diagrams (1-2) to the reactions below. You can use
one diagram more than once.
A concerted (single step) kinetically-controlled, exergonic reaction that
can lead to 2 different products.
A concerted (single step) thermodynamically-controlled, exergonic
reaction that can lead to 2 different products.
A situation where Hammond’s Postulate does NOT hold.
G
1
G
2
Progress
3.
Progress
(12 points) For each of the reactions shown below, indicate if the mechanism is SN1, SN2,
E1 or E2.
a)
Br
CH3OH
Heat
b)
Br
NaOEt
Br
CH3OH
Heat
c)
OCH3
3
d)
OTs
4.
CH2SNa
SCH3
(20 points) Provide the expected organic product from each of the reactions below.
Show any relevant stereochemistry. If you believe that no reaction will occur, write “No
Reaction.”
a)
H2SO4, H 2O
b)
O
HCl
c)
OH
TsCl
pyridine
CH3
d)
Br
CH3
5.
tBuO K
(5 points) Draw a Newman projection for the starting material for the elimination
reaction shown below, in the required conformation for the reaction.
Br
Br
NaOEt
Br
4
6.
(7 points) Using the data in the table, estimate DH for the reaction below.
CH2
CH3
Br
HBr
CH3CH2
CH3CH2
CH3
CH3
Bond Dissociation Energies:
H-CH3
H-CH(CH3)2
H-C(CH3 )3
Br-CH3
7.
100.3
96.0
93.3
70
Br-Br
H-Br
H-OH
46.1
87.6
119
CH3-CH3
CH2=CH 2 (p bond only)
CH2=CH 2 (total)
90
66
172
(15 points) Provide the reagents needed to execute the following reactions. Provide
“complete” reagents: If you intend to use bromide ion, specify a reagent such as (NaBr)
rather than just Br-.
a)
Cl
CN
b)
Cl
c)
H
Cl
5
8.
(5 points) a-Chloroamines are quite unstable, as they undergo a very facile elimination
reaction. Draw the mechanism and the product of this elimination.
H
N
9.
Cl
?
(6 points) The b-chloroamine below reacts to give the b-aminoalcohol shown. Notice
that the N-C2 bond has been replaced by a N-C1 bond. Draw a viable mechanism for this
reaction.
H
N
Cl
2
3
1
NaOH, H2O
H
N
OH
1
2
3
6
9.
(3 points) Who is the Hammond Postulate named after? Do not exceed the space
provided.
END OF EXAM
7