CHM 114 Stereochemistry
Stereocenters
1. How many stereocenters are there in 2,2,4-tribromo-3-methyl-1-pentanol?
(A)
2
(B)
3
(C)
4
(D)
5
2. How many stereocenters are there in 2,3-dibromo-4-methylpentane?
(A)
1
(B)
2
(C)
3
(D)
4
3. How many stereocenters are there in cyclohex-3-ene-1,2-diol?
(A)
1
(B)
2
(C)
3
(D)
4
4. How many stereocenters are present in the following structure?
O
N
HO
O
NH
N
N
NH 2
H
HO OH
(A)
1
(B)
2
(C)
3
(D)
4
5. How many stereocenters are present in the following structure?
NH 2
N
HO
O
N
O
HO OH
(A)
1
(B)
2
(C)
3
(D)
4
Chirality
6. Which of the following molecules are chiral?
1. trans-1-chloro-2-methylcyclopropane
2. cis-1-chloro-2-methylcyclopropane
3. 1-chloro-1-methylcyclopropane
4. cis-1,2-dichlorocyclopropane
(A)
1 and 4
(B)
2 and 3
(C)
1 and 2
(D)
3 and 4
7. Which of the following molecules are chiral?
1. 1-chloro-2-methylpropane
2. 2-bromobutane
3. 3-chloropentane
4. 2-chloro-3-methylbutane
(A)
1 and 4
(B)
2 and 3
(C)
1 and 3
(D)
2 and 4
8. Which of the following molecules are achiral?
1. trans-1,2-cyclohexanediol
2. cis-1,2-cyclohexanediol
3. trans-1,4-cyclohexanediol
4. trans-1,3-cyclohexanediol
(A)
1 and 4
(B)
2 and 3
(C)
1 and 2
(D)
3 and 4
9. Which of the following molecules are chiral?
1. 4-chlorocyclopentene
2. 2-chloro-3,4-dimethylpentane
3. trans-2-chlorocyclohexanol
4. cis-3,5-dichlorocyclopentene
(A)
1 and 4
(B)
2 and 3
(C)
1 and 2
(D)
3 and 4
10. Which of the following molecules are chiral?
1. cis-2-chlorocyclohexanol
2. 2-chloropentane
3. 2-chloro-1-pentene
4. 2-chloropropane
5. 2-chlorobutane
6. cis-3,5-dichlorocyclopentene
(A)
1, 2, 5
(B)
2, 4, 6
(C)
1, 2, 4
(D)
4, 5, 6
Stereoisomers
11. What is the maximum number of stereoisomers possible for the following structure?
O
HOH 2C
HO
(A)
2
(B)
4
(C)
8
(D)
16
OH
OH
12. How many total stereoisomers are possible for 1,2,3,4-pentanetetraol, and of these, how many are chiral?
OH
OH
HO
OH
(A)
8 and 4
(B)
8 and 8
(C)
6 and 4
(D)
4 and 4
13. There are X isomers of dimethylcyclopropane of which Y are chiral. Select the right numbers for X and Y.
X
Y
(A)
3
1
(B)
2
2
(C)
2
0
(D)
4
2
14. Whcih of the following are stereoisomers?
1
3
2
(A)
1 and 2
(B)
1 and 3
(C)
1 and 4
(D)
2 and 3
4
15. Which of the following structures have the meso form?
H
H
H
H
OH
OH
OH
H
1
HO
H
HO
CH3
H
OH
H
H
2
H
H3C
HO
HO
(A)
1 and 2
(B)
3 and 4
(C)
1 and 3
(D)
2 and 3
OH
H
H
CH3
3
CH3
OH
H
OH
H
4
H
H
H3C
16. The following structures are stereoisomers. Which are enantiomers?
CH3
H
OH
H
OH
H
OH
CH3
1
(A)
1 and 2
(C)
1 and 4
CH3
CH3
H
OH
H
OH
HO
H
H
OH
H
OH
HO
H
CH3
CH3
3
2
(B)
3 and 4
(D)
CH3
HO
H
H
OH
H
OH
CH3
4
2 and 3
17. For the following sets of structures, which pairs are enantiomers?
(A)
1 and 2
(B)
1 and 3
(C)
2 and 3
(D)
none
Br
1
H
Br
F
Cl
H
H
CH3
F
3
F
H3C
Cl
OH
H
H3C
H3CH2C
Cl
F
F
2
H
OH
H
H3C
CH2CH3
18. What relationship do the following structures have?
(A)
enantiomers
(B)
diastereomers
(C)
structural isomers
(D)
identical
19. What relationship do the following structures have?
H
CH3
H
H
CH3
CH3
(A)
enantiomers
(B)
CH3
diastereomers
(C)
structural isomers
(D)
conformational isomers
H
20. What relationship do the following structures have?
H
D
Cl
Cl
H
CH3
D
CH3
(A)
enantiomers
(B)
diastereomers
(C)
structural isomers
(D)
identical
21. What relationship do the following structures have?
CH3
OH
H3C
H
H
H
Cl
CH3
H3C
Cl
OH
H
(A)
enantiomers
(B)
diastereomers
(C)
structural isomers
(D)
identical
22. Which of the following structures are pairs of enantiomers?
OH
H
CH 3
CH 2CH 3
1
OH
CH 2CH 3
H3C
H
OH
2
H3CH 2C
H
CH 3
HO
H
3
(A)
1 and 2
(B)
1 and 3
(C)
2 and 4
(D)
none
CH 2CH 3
CH 3
4
23. What is the total number of pairs of enantiomers for the following molecules?
OH
CH3CHCH 2CH2CH3
OH
OH
CH3CH2CHCH 2CH3
HOCH 2CH2CH2CH2CH3
(A)
2
(B)
4
(C)
6
(D)
8
CH3CH2CHCH 3
24. How many pairs of diastereomers does 1,2-dimethylcyclopentane have?
(A)
1
(B)
2
(C)
3
(D)
4
25. Which of the following molecules can have diastereomers but not enantiomers?
OH
H3CC CCH2CH3
1 OH
3
2
OH
H3CHC CHCH 2CH3
H2C CHCH 2CH3
4
(A)
1 and 3
(B)
3 and 4
(C)
2 and 5
(D)
4 and 6
H3C
5
6
26. Which of the following molecules can have both diastereomers and enantiomers?
OH
OH
CH3
H3C
OH
(A)
(B)
H3CHC CHCH 3
(C)
(D)
Molecule A
The R/S System
27. What is the R,S configuration for the following structure (remember that this is a Fisher projection)?
CH2CH2CH3
HO
H
HO
H
CH2CH3
(A)
3R, 4R
(B)
3S, 4S
(C)
3R, 4S
(D)
3S, 4R
28. What is the R,S configuration for the following structure?
CO2H
H
HO 2C
CH2CO2H
H
Cl
(A)
2R, 3R
(B)
2R, 3S
(C)
2S, 3R
(D)
2S, 3S
29. Which of the following structures are designated S?
Cl
CH3
Cl
1
Cl
H
OH
H
H
F
Br
2
H2N
H
H3C
(A)
1 and 2
(B)
2 and 3
(C)
2 and 4
(D)
1 and 3
H3CH2C
C(CH3)3
H3C
3
CH3
4
30. Which of the following structures are designated S?
H
H3C
H
F
Br
H2CHC
1
H
(H3C)3C
2
CHCH 2
H3CH2C
CH(CH 3)2
H3C
3
(A)
1 and 2
(B)
1 and 3
(C)
2 and 3
(D)
all
31. Which of the following structures have an R configuration?
H
H3C
CH2Cl
Br
1
(A)
1 and 2
(C)
2 and 4
CH3
CH2OH
CH2Br C2H5
Cl
Br
CH2Cl
CHCl 2
3
2
(B)
1 and 3
(D)
CH3
H
CH3
CH3
4
3 and 4
32. What is the enantiomeric excess for the reaction that gives 66% of the S enantiomer and 33% of the R form?
(A)
25%
(B)
33%
(C)
50%
(D)
75%
33. The specific rotation of dextrarotatory tartaric acid is +12.7 degrees. A mixture of dextrarotatory and
levorotatory tartaric acid has a specific rotation of –6.35 degrees. What is the optical purity of the mixture?
(A)
25%
(B)
33%
(C)
50%
(D)
75%