PRACTICE SECOND HOUR EXAM B
1.
For the molecule shown, which column gives the best answers to the questions given?
CH3
HO
2.
CH3
C
C
H
H
H
A
B
C
D
Is the molecule chiral?
No
No
Yes
Yes
How many stereocenters does it contain?
0
2
1
2
Is it superposable on its mirror image?
Yes
Yes
No
No
Does it have a plane of symmetry?
Yes
Yes
No
No
Is it optically active?
No
No
Yes
Yes
Is it a meso compound?
No
Yes
No
No
Which of the following compounds undergoes E1 reactions most readily?
A.
B.
C.
D.
3.
ORGANIC CHEMISTRY 2210
1-chloropentane
2-chloropentane
2-chloro-2-methylbutane
2,2-dimethyl-1-chloropropane
The reaction shown yields:
CH3 CH2
C
H
A.
B.
C.
D.
CH2 CH2 CH2 Br + Zn + HBr ------> ?
CH3
a pair of enantiomers
a single chiral compound without its enantiomer
a meso compound
only achiral compounds having no stereocenters
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4.
What is the name of the compound shown?
Cl
H
CH2 CH3
CH(CH 3 )2
H
H
A.
B.
C.
D.
5.
4-chloroheptane
3-chloro-2-methylhexane
1-chloro-1-isopropylbutane
1-chloro-1-isopropyl-2-ethylethane
Which of the following statements about the relative stabilities of the structures shown is
TRUE?
I
A.
B.
C.
D.
6.
I has more steric strain.
I has more bond angle strain.
II has more steric strain.
II has more bond angle strain.
Which of the following structures of cyclohexane has the most bond angle strain?
A.
7.
II
B.
C.
What is the relationship between the structures shown?
CH3 CH2
CH3 CH2
Br
CH3
C
H
C
H
|
|
CH3
Br
A.
B.
C.
D.
Structural isomers
Diastereomers
Enantiomers
Same compound
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D.
8.
What is the major organic product of the reaction sequence shown?
CH3 Br H2 , Pt Br2 , light
CH3 C≡CNa ---------> --------> -------------> ?
A.
B.
C.
D.
9.
CH3 C≡CH
CH3 C≡CCH3
CH3 CH2 CH2 CH2 Br
CH 3 CH2 CHBrCH 3
How many tetrahedral stereocenters are there in the compound shown?
H3 C
A. 1
10.
B. 2
CO2 H
C. 3
D. 4
What is the relationship between the pair of compounds shown?
CHO
H
OH
HO
H
H
OH
CHO
HO
H
H
HO
CH2 OH
A. Same compound
11.
OH
H
CH2 OH
B. Enantiomers
C. Diastereomers
What is the configuration of the compound shown?
H
Br
CH3
Br
A. (2R,3R)
H
CH2 CH3
B. (2S,3S)
C. (2R,3S)
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D. (2S,3R)
D. Constitutional isomers
12.
SN1 reactions occur most rapidly in which of the following substrates?
A.
13.
B.
Br
I
Br
C.
I
D.
CH3
CH3
What is the major organic product of the SN2 reaction shown?
CH3
H
H
H
I
+ Br
-----> ?
CH3
A. 1-butene
14.
B. 2-butene
D. S-2-bromobutane
Which of the following molecules has a plane of symmetry?
H
A. Br
C
NH 2
CH3
B.
CH3
15.
C. R-2-bromobutane
H
H
CO2 H
H
NH 2
F
C.
CO2 H
D.
C—C
H
Cl
NH 2
H
F
H
H
Br
Which of the following compounds is the best starting material for the reaction shown?
?
A.
CH2 Br
CH3 O
---------------->
CH3 CH2 OH
B.
CH3
Br
CH3
C. Br
78
CH3
D.
Br
16.
Hydrogenation of a pure sample of the alkene shown gives a product that is ______.
CH=CH 2
H
CH3
H2 , Ni
------------> ?
CH2 CH3
A.
B.
C.
D.
17.
Which of the following changes increases the rate of an SN1 reaction?
A.
B.
C.
D.
18.
a linear alkyne
a racemic mixture
a pure enantiomer
an achiral compound
Increasing the temperature
Using a less polar solvent
Decreasing the concentration of substrate
Increasing the concentration of nucleophile
Which of these compounds is a major organic product of the sequence of reactions shown?
S
H2 , Pt Cl2 , light
CH3 CH=CH 2 ---------> ------------> ----------------> ?
19.
A. CH3 CH2 CH2 Cl
B. ClCH2 CH2 CH2 S
C. CH3 CH2 CH2 S
D. CH2 =CHCH 2 S
Which of the following reaction sequences gives (CH3 )2 CHCH 2 CH2 CH3 as the major
organic product?
A.
NaNH 2 CH3 Br H2 , Ni
(CH3 )2 CHCH 2 C≡CH ----------> ---------> ----------> ?
B.
(CH3 )2 CHC≡CH
C.
NaNH 2 Zn, HCl
(CH3 )2 CHCH 2 C≡CH ----------> -----------> ?
D.
NaNH 2 Zn, HCl
(CH3 )2 CHC≡CH ----------> -----------> ?
NaNH 2 CH3 Br H2 , Ni
----------> ---------> ----------> ?
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20.
Which of these is the gauche conformation of 1-bromobutane?
H
Br
A.
C
H
C.
21.
C
C
H
H
H
C
CH2 CH3
H
CH2 CH3
H
H
D.
C
Br
H
CH2 CH3
C
C
H
H
B. 64%
C. 36%
D. 32%
Which of these represents the most stable conformation of cis-4-isopropylcyclohexanol?
H
A.
H
B.
CH(CH 3 )2
H
CH(CH 3 )2
HO
HO
H
CH(CH 3 )2
C.
CH(CH 3 )2
D.
H
H
H
HO
HO
23.
H
A sample of R-2-chloropentane has an optical purity (enantiomeric excess) of 36%. What
percentage of this sample is S-2-chloropentane?
A. 68%
22.
C
H
Br
H
B.
H
H
Br
CH2 CH3
H
The reaction of methanol with tert-butyl bromide gives methyl tert-butyl ether,
(CH3 )3 COCH 3 , as the major product. If the concentration of methanol is tripled, what
happens to the rate of the reaction?
A.
B.
C.
D.
It triples.
It remains the same.
It decreases to 1/3 of the original rate
It doubles.
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24.
What is the relationship between the structures shown?
CH3 Br
CH3 CH3
\
/
\
/
C=C
C=C
/
\
/
\
H
CH 3
H
Br
A.
B.
C.
D.
25.
Same compound
Enantiomers
Diastereomers
Constitutional isomers
The two compounds whose structures are shown have _____ melting points. Their rotation
of plane-polarized light would be _____.
H
H
CH3 CH3
CH3
H
A.
B.
C.
D.
CH3
H
equal . . . equal in magnitude but in opposite directions
equal . . . identical
different . . . both equal to zero
different . . . different
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