CH 242 Organic Chemistry Exam # 1 Winter 2002 Name _________________
100 pts total (multiple choice – 3 pts each)
1. Which of the following is a true statement?
a. The 1,2-addition product is always the kinetic product.
b. If the 1,2-product is the kinetic product, then the 1,4-product must be the thermodynamic
product.
c. The structure of the reactant determines which products are the kinetic and thermodynamic
products.
d. The 1,4-addition product is always the thermodynamic product.
e. Mild reaction conditions favor the thermodynamic product.
2. Which of the following alkyl halides will form a constitutional isomer in an SN1 reaction that is
different than the one formed in an SN2 reaction?
a.
b.
c.
d.
e.
2-chloropentane
3-chloropentane
2-chloro-4-methylhexane
2-chloro-3-methylhexane
2-chloro-5-methylhexane
3. The E1 reaction of 3-chloro-2,2-dimethylbutane forms 2,3-dimethylbutene in several steps.
Which step does not belong in the sequence?
a.
b.
c.
d.
e.
formation of a tertiary carbocation
heterolytic dissociation of the carbon-chlorine bond
a 1,2-methyl shift
formation of a secondary carbocation
loss of a hydride ion
4. Which of the following is not a true statement?
a. Under SN2 and E2 conditions, tertiary alkyl halides give both substitution and elimination
products.
b. Under SN2 and E2 conditions, secondary alkyl halides give both substitution and elimination
products.
c. Under SN1 and E1 conditions, secondary alkyl halides give both substitution and elimination
products.
d. Under SN2 and E2 conditions, primary alkyl halides give primarily substitution products.
e. Under SN1 and E1 conditions, tertiary alkyl halides give both substitution and elimination
products.
5. Name each of the following compounds: (3 pts each)
1
a. CH3 CH=CHCH(OH)CH 2 CH 3
H
b,
H
CH3
c.
H3 C
CH3
C(CH3 )2 H
d.
6. Give the products of the following reaction Equivalent amounts of reagents are used. (5 pts)
+
Br2
7. For each of the following reactions, give the major 1,2- and 1,4- addition products, and indicate which is
the kinetic product and which is the thermodynamic product. Explain your reasoning. (10 pts)
2
a.
b.
CH2 =CHCH=C(CH 3 )2
+
HBr
CH=CHCH 3
HCl
+
8. Give the products of the following Diels-Alder reactions. (10 pts)
a.
b.
CH2 =CHC(CH 3 )=CH 2
CH 3
+
+
HC
CH
CH3
3
9. Give the configuration(s) of the main product(s) that will be obtained from the following reactions of the
following secondary alkyl halides with the indicated nucleophile (remember to show the correct
stereochemistry of the products): (9 pts)
CH2 CH3
a.
C
H3 C
H
+
CH3 O
-
high concentration
Br
CH2 CH 3
b.
C
H3 C
DMSO
H
CH 3 OH
+
CH 3 OH
Br
DMF
CH 2 CH3
c.
C
H3 C
H
Br
+
(CH3 )3 CO
-
high concentration
10. Draw the reaction coordinate diagrams for each of the reactions in problem # 9.
(6 pts)
11. Show the reaction mechanism for the reaction b in problem # 9 using arrows to show the paths of the
electrons . (5 pts)
4
12. S-Adenosylnethionine (SAMe) is sold as a natural antidepressant in health food stores. What is the
chemical role in the cell of this compound? (2 pts)
13. Propose a mechanism for the following reaction: (5 pts)
CH3
CH3 OH
C(CH 3 )2 Cl
CH 3
14. What is the major product formed when trans-1-bromo-2-ethylcyclohexane undergoes an E2
elimination? Why? (5 pts)
5
15. Describe how the following starting product could be prepared from the given starting material. (10
pts)
O
16. The acid catalyzed dehydration of 2-methyl –2-butanol is the reversible reaction we did in the lab.
a. Show the mechanism of this reaction. (5 pts)
b. Which product is predominant and why? (2 pts)
6
c. How did we displace this reversible reaction to the right (Le Chatelier’s principle)? (2 pts)
7