Name:_______________________________
Organic Chemistry Chapter 3 Test
Identify the conformation of butane shown below:
CH3
H
H3C
1.
H
H
H
A)
B)
C)
D)
anti
gauche
skewed
eclipsed
2. What is the IUPAC name of the compound shown in the following Newman projection?
CH3
H
H3C
H3C
A)
B)
C)
D)
H
CH3
1,1,2,2-tetramethylethane
1,2-dimethylethane
2,2,3,3-tetramethylbutane
2,3-dimethylbutane
3. What is the IUPAC name of the compound shown below?
CH3
CH(CH3)2
H3C
H
A)
B)
C)
D)
H
H
1,2,3-trimethylbutane
2,3-dimethylpentane
2,3,4-trimethylpentane
2-isopropylbutane
Page 1
4. What is the dihedral(torsion) angle between the two bromine atoms in the following
sawhorse drawing?
Br
CH3
Br
H
A)
B)
C)
D)
H
00
300
600
900
5.
A)
B)
C)
D)
At room temperature the various conformations of butane:
do not interconvert, only the anti form is present.
do not interconvert, but all conformations are present.
interconvert slowly.
interconvert rapidly.
CH3
6. Which statement is correct concerning the relative stabilities of the two conformations,
A and B, below:
CH3
H
H
H3C
H
CH3
H
CH3
A)
B)
C)
D)
A
B
A is more stable.
B is more stable.
A and B are equal in stabilities.
A and B are not equal in stability, but the preferred conformation cannot be determined
by inspection.
Page 2
7. Which statement is correct concerning the relative stabilities of the two conformations,
A and B, below:
CH3
CH3
H
H
H
CH3
H3C
H
H3C
H
CH3
H
A)
B)
C)
D)
A
B
A is more stable.
B is more stable.
A and B are equal in stabilities.
A and B are not equal in stability, but the preferred conformation cannot be determined
by inspection.
8. What is the IUPAC name of the following compound?
H
CH3
H3C
A)
B)
C)
D)
H
trans-1,4-dimethylcyclohexane
cis-1,4-dimethylcyclohexane
trans-1,3-dimethylcyclohexane
cis-1,3-dimethylcyclohexane
9. Identify the relationship between the following two structures.
CH3
CH3
H
H
H
and
CH3
H
HC
3
H CH3
A)
B)
C)
D)
CH3
constitutional isomers
stereoisomers
different conformations of the same compound
idential
Page 3
H
10. Identify the relationship between the following two structures.
H
H
CH3
H3C
A)
B)
C)
D)
H
and
H
H
CH3
constitutional isomers
stereoisomers
different conformations of the same compound
identical
11. Identify the relationship of the two compounds below:
H
CH3
and
H
A)
B)
C)
D)
CH3
CH3
H3C
CH3
identical
constitutional isomers
stereoisomers
different conformations of the same compound
Page 4
H
12. Identify the chair conformation of the following compound which is the correct
stereoisomer and in its most stable conformation.
CH(CH3)2
CH3
CH(CH3)2
H
1)
CH(CH3)2
H3C
3)
H
H3C
H
H
CH(CH3)2
H
2)
CH(CH3)2
H
H
H
CH3
CH3
A)
B)
C)
D)
4)
is 1
is 2
is 3
is 4
Page 5
13. Which isomer of 1-tert-butyl-3-ethyl-5-methylcyclohexane below is thermodynamically
the most stable?
t-Bu
t-Bu
3)
1)
Me
Et
Me
Et
t-Bu
t-Bu
4)
2)
Me
Me
Et
Et
A)
B)
C)
D)
is 1
is 2
is 3
is 4
14.
A)
B)
C)
D)
What would the C⎯C⎯C bond angles be in a planar cyclohexane?
600
900
109.50
1200
15. The IUPAC name of the following compound is:
CH3
H
H
CH3
CH2
H
CH2
H
H
cis-1,2-dimethylcyclohexane
trans-1,2-dimethylcyclohexane
1,1-dimethylcyclohexane
cis-1,3-dimethylcyclohexane
H
A)
B)
C)
D)
Page 6
16. Identify the relationship between the following two Newman projections.
CH3
H
H
H3C
H
H3C
and
H
H
H3C
CH3
A)
B)
C)
D)
H
CH3
identical
stereoisomers
different conformations of the same compound
constitutional isomers
17. Below is a diagram for torsion angle vs. potential energy for the rotation of C2 and C3 in
butane. Draw a Newman projection for each position on the diagram and label it as eclipsed,
gauche or anti.
A
A
C
C
E
E
B
D
0
60
120
180
240
300
Degrees of Rotation θ
Position A
Position D
Position B
Position E
Position C
Position F
Page 7
360
18. Draw the most stable conformation of the following compounds.
a. cis-1-isopropyl-3-methylcyclohexane
b.
H3C
CH3
CH3
c.
CH3
CH3
H3C
CH3
Page 8
Answer Key
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
B
D
B
C
D
C
B
A
C
B
C
B
A
D
A
C
Page 9