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Problem 83
The specific rotation of (R)-(+)-glyceraldehyde is +8.7. If the observed specific rotation of a mixture of (R)-glyceraldehyde and (S)-glyceraldehyde is +1.4, what percent of glyceraldehyde is present as the R enantiomer?
Problem 84a,b
Indicate whether each of the following structures is (R)-2-chlorobutane or (S)-2-chlorobutane:
a.
b.
Problem 84c,d
Indicate whether each of the following structures is (R)-2-chlorobutane or (S)-2-chlorobutane:
c.
d.
Problem 84e,f
Indicate whether each of the following structures is (R)-2-chlorobutane or (S)-2-chlorobutane:
e.
f.
Problem 85
Butaclamol is a potent antipsychotic that has been used clinically in the treatment of schizophrenia. How many asymmetric centers does it have?
Problem 86
Explain how R and S are related to (+) and (-).
Problem 87
Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?
a.
b.
Problem 88b
Which stereoisomers are optically inactive?
Problem 89a,b
What is the configuration of the asymmetric centers in the following compounds?
a.
b.
Problem 90(5-8)
Identify
5. achiral compounds
6. meso compounds
7. enantiomers
8. diastereomers
Problem 90a
Draw all the isomers with molecular formula C6H12 that contain a cyclobutane ring.
Problem 90c(1,2,3,4)
Identify
1. constitutional isomers
2. stereoisomers
3. cis–trans isomers
4. chiral compounds
Problem 91
A compound has a specific rotation of -39.0. A solution of the compound (0.187 g/100 mL) has an observed rotation of -6.52° when placed in a polarimeter tube 10 cm long. What is the percent of each enantiomer in the solution?
Problem 92a,b
Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?
a.
b.
Problem 92c,d
Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?
c.
d.
Problem 93a,b,c
Draw structures for the following:
a. (S)-1-bromo-1-chlorobutane
b. (2R,3R)-2,3-dichloropentane
c. an achiral stereoisomer of 1,2-dimethylcyclohexane
Problem 93d
Draw structures for the following:
d. a chiral stereoisomer of 1,2-dibromocyclobutane
Problem 93e
Draw structures for the following:
e. two achiral stereoisomers of 3,4,5-trimethylheptane
Problem 94
For each of the following structures, draw the most stable chair conformer.
a.
b.
Problem 95
Explain why the enantiomers of 1,2-dimethylaziridine can be separated even though one of the “groups” attached to nitrogen is a lone pair.
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Problem 96
A sample of (S)-(+)-lactic acid was found to have an enantiomeric excess of 72%. How much R isomer is present in the sample?
Problem 98a
Using the wedge-and-dash notation, draw the nine stereoisomers of 1,2,3,4,5,6-hexachlorocyclohexane.
Problem 98b
From the nine stereoisomers, identify one pair of enantiomers.
Problem 99c
What is the configuration of each of the asymmetric centers in the following compounds?
c.
Problem 100
Tamiflu is used for the prevention and treatment of flu. What is the configuration of each of its asymmetric centers?
Problem 101
A student decided that the configuration of the asymmetric centers in a sugar such as D-glucose could be determined rapidly by simply assigning the R configuration to an symmetric center with an OH group on the right and the S configuration to an symmetric center with an OH group on the left. Is he correct?
Problem 102a
Draw the two chair conformers for each of the stereoisomers of trans-1-tert-butyl-3-methylcyclohexane.
Problem 102b
For each pair, indicate which conformer is more stable.
Problem 105a,b
What is the configuration of each of the asymmetric centers in the following compounds?
a.
b.
Problem 105c,d
What is the configuration of each of the asymmetric centers in the following compounds?
c.
d.
