1
Exam 4 Answer Key, CH343, Spring 2008
______
Name
This exam consists of several parts of unequal difficulty. Look over the whole exam right now, and start on something you know well. If you don’t know something, skip it, and come back to it later. Use your time wisely.
Keep Your Eyes On Your Own Paper!
Grading Summary
Page 2. ______(24)Page 5. ______(16)
Page 3. ______(24)Page 6. ______(8)
Page 4. ______(12)Page 7. ______(16)
Bonus! ______(≤5)
Total ______(100)
A Partial Periodic Table of the Elements
1A / IIA / IIIB / IVB / VB / VIB / VIIB / VIII / IB / IIB / IIIA / IVA / VA / VIA / VIIA / VIIIA1
H
1.01 / 2
He
4.00
3
Li
6.94 / 4
Be
9.01 / 5
B
10.8 / 6
C
12.0 / 7
N
14.0 / 8
O
16.0 / 9
F
19.0 / 10
Ne
20.2
11
Na
23.0 / 12
Mg
24.3 / 13
Al
27.0 / 14
Si
28.1 / 15
P
31.0 / 16
S
32.1 / 17
Cl
35.5 / 18
Ar
40.0
19
K
39.1 / 20
Ca
40.1 / 21 / 22 / 23 / 24 / 25 / 26 / 27 / 28 / 29 / 30 / 31
Ga
69.7 / 32
Ge
72.6 / 33
As
74.9 / 34
Se
79.0 / 35
Br
79.9 / 36
Kr
83.8
37 / 38 / 39 / 40 / 41 / 42 / 43 / 44 / 45 / 46 / 47 / 48 / 49 / 50 / 51 / 52 / 53
I
127 / 54
Give the major organic product of each of the following reactions (24).
a. /b. /
c. /
d. /
e. /
f. /
Give the reagents and reaction conditions needed to accomplish the following transformations. An arrow may require more than on synthetic step (24).
a. /b. /
c. /
d. /
e. /
f. /
In their synthesis of physostigmine, Julian and Pikl used the following sequence of reactions to methylate their intermediate amine (12).
a. Explain what each step did. Draw the structures of the intermediates after steps 1 and 2: you do not have to draw the mechanisms. You can abbreviate the structure of the starting amine as R-NH2.
Step 1 makes the imine / Step 2 alkylates the imine NStep 3 hydrolyzes the iminium salt
b. What would have happened if he had done the following sequence of steps (assuming LiAlH4 had been available to Julian)? Explain your reasoning.
Step 1 makes the amide / Steps 2 & 3 reduce BOTH amides to aminesGive reasonable arrow-pushing mechanisms for the following reactions (16).
a.
See Key Mechanism 22-9 on page 1057-8 and Key Mechanism 22-11 on page 1060.
b.
Multiple Choice: Choose the best answer for each question (8).
1.B
______/ The following reaction is an example of
A. An aldol condensation
B. A Claisen condensation
C. A conjugate addition
D. A Robinson Annulation
2.
C
______/ The following reaction is an example of
A. An aldol condensation
B. A Claisen condensation
C. A conjugate addition
D. A Robinson Annulation
3.
B
______/ The major organic product of the following reaction sequence is:
A. B. C. D.
4.
D
______/ Which of the following was a British Chemist?
A. Percy Julian
B. Arthur Michael
C. Rainer Claisen
D. Robert Robinson
Provide reasonable syntheses of the following compounds from the indicated starting materials, plus any other reagents. These syntheses require more than one step, so one step syntheses will receive no credit (16).
ProductStarting Material
a. This is an acetoacetic ester synthesis.
b. You can’t directly alkylate an ester, so you have to do a Claisen reaction, and then reduce the ketone in steps to an alkane.
Bonus: On the last homework, Dr. Hathaway proposed the following reaction would occur. If addition, another reaction occurs to form a product with two rings. Propose a structure for the two-ring product, and a reasonable mechanism by which it forms.