Seat Assignment: _________________
Elementary Organic Chemistry
Chem 209
Exam I
October 2, 2008
Name (print): _____________________
Name (sign): _____________________
Student Number: __________________
Multiple Choice Answers (one letter per question, 3 points each)
5. _____________
11. _____________
6. _____________
12. _____________
7. _____________
13. _____________
8. _____________
14. _____________
9. _____________
15. _____________
10. _____________ 16. _____________
subtotal: _______________
Written Answer Questions (overpage, 4 points each): subtotal: __________________
Total: ________________
Please note: pencil is recommended!
1
Written Answer Questions (4 points each)
1.
Draw, in the box, the structure of a compound or ion that has a formal +1 charge
on nitrogen.
2.
Draw, in the box, the major product of the following reaction.
3.
By using the template below, draw the structure of 1,1-dichlorocyclohexane
(C6H10Cl2) in the most stable conformation. Try to represent the positions of the
two chloro atoms as accurately and artistically as possible. Then, carefully draw
in the 10 hydrogen atoms, showing their axial or equatorial disposition.
4.
Draw in the box, one resonance structure of the carbocation intermediate in the
Friedel-Crafts para alkylation of anisole (see problem 12).
2
Multiple Choice Questions (3 points each)
5.
Propose reagents for accomplishing the following transformation.
A.
B.
C.
D.
E.
O2, heat
H2, Pd (catalyst)
H2O2, heat
H2O, NaOH (catalyst)
H2O, H2SO4 (catalyst)
6. The energy diagram below represents the mechanism of the addition of H-Br to 1methylcyclopentene, which is reversible. How many steps are there in the reverse
reaction (i. e., loss of H-Br)?
A.
B.
C.
D.
E.
7.
1
2
3
4
5
For the reaction in question 6 above, which letter represents the loss of energy
(endothermicity) for the reverse reaction?
A.
B.
C.
D.
E.
a
b
c
d
e
3
8.
Some reactions that are very favored thermodynamically nevertheless proceed
very slowly. Why?
A.
B.
C.
D.
E.
9.
These reactions are reversible
The products have very strong bonds
The products have very weak bonds
There is a high energy of activation
There are many steps in the mechanism
The para-bromination of nitrobenzene initially gives rise to a cyclohexadienyl
cation. Its three resonance structures are shown below. Rationalize based on
these structures why the para position is not a favored position for this
bromination compared with meta.
A.
B.
C.
D.
E.
One of these resonance structures has particularly low energy
One of these resonance structures has particularly high energy
The nitro group is electron-releasing relative to H
The nitro group is electron-releasing relative to Br
The bromo atom is bulky and sterically repels the nitro group
4
10.
Give the major product in the catalytic hydrogenation reaction of
methylcyclopentene (shown below), where D2 is used instead of H2. Hint: recall
the mechanism of this reaction. D (deuterium) is the heavy isotope of H.
11.
All of the carbons of which molecule, in its most stable conformation, lie in a
single plane? Hint: you may find it helpful to build models.
A.
B.
C.
D.
E.
12.
2,2-dimethylpropane
2-methylpropane
methylcyclohexane
1-methylcyclohexene
trans-2-butene
Choose the best reaction conditions for the Friedel-Crafts alkylation of anisole
(shown below).
A.
B.
C.
D.
E.
(CH3)3C-Cl, AlCl3
(CH3)3C-C(CH3)3, AlCl3
(CH3)3C-C(=O)Cl, AlCl3
(CH3)3C-Cl, HNO3
There are no good reaction conditions for this transformation
5
13.
What is the molecular formula for the line structure shown below?
A.
B.
C.
D.
E.
14.
C10H8
C10H10
C10H12
C9H10
C9H5
Arrange the following liquids in order of least-to-most soluble in water:
I: n-decane
A.
B.
C.
D.
E.
15.
III: 2-propanol
I < II < III
I < III < II
II < III < I
III < I < II
III < II < I
Which of the following is chiral?
A.
B.
C.
D.
E.
16.
II: 1-decanol
methanol
1,2-dichlorobenzene
trans-1,2-dibromocyclohexane
3-bromopentane
benzoic acid
Arrange the following carbocations in order of increasing stability, least stable
first.
A.
B.
C.
D.
E.
I < II < III
I < III < II
II < III < I
III < I < II
III < II < I
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