Indietro
Problema 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?
Problema 84a,b
Indicate whether each of the following structures is (R)-2-chlorobutane or (S)-2-chlorobutane:
a.
b.
Problema 84c,d
Indicate whether each of the following structures is (R)-2-chlorobutane or (S)-2-chlorobutane:
c.
d.
Problema 84e,f
Indicate whether each of the following structures is (R)-2-chlorobutane or (S)-2-chlorobutane:
e.
f.
Problema 85
Butaclamol is a potent antipsychotic that has been used clinically in the treatment of schizophrenia. How many asymmetric centers does it have?
Problema 86
Explain how R and S are related to (+) and (-).
Problema 87
Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?
a.
b.
Problema 88b
Which stereoisomers are optically inactive?
Problema 89a,b
What is the configuration of the asymmetric centers in the following compounds?
a.
b.
Problema 90(5-8)
Identify
5. achiral compounds
6. meso compounds
7. enantiomers
8. diastereomers
Problema 90a
Draw all the isomers with molecular formula C6H12 that contain a cyclobutane ring.
Problema 90c(1,2,3,4)
Identify
1. constitutional isomers
2. stereoisomers
3. cis–trans isomers
4. chiral compounds
Problema 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?
Problema 92a,b
Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?
a.
b.
Problema 92c,d
Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?
c.
d.
Problema 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
Problema 93d
Draw structures for the following:
d. a chiral stereoisomer of 1,2-dibromocyclobutane
Problema 93e
Draw structures for the following:
e. two achiral stereoisomers of 3,4,5-trimethylheptane
Problema 94
For each of the following structures, draw the most stable chair conformer.
a.
b.
Problema 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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Problema 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?
Problema 98a
Using the wedge-and-dash notation, draw the nine stereoisomers of 1,2,3,4,5,6-hexachlorocyclohexane.
Problema 98b
From the nine stereoisomers, identify one pair of enantiomers.
Problema 99c
What is the configuration of each of the asymmetric centers in the following compounds?
c.
Problema 100
Tamiflu is used for the prevention and treatment of flu. What is the configuration of each of its asymmetric centers?
Problema 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?
Problema 102a
Draw the two chair conformers for each of the stereoisomers of trans-1-tert-butyl-3-methylcyclohexane.
Problema 102b
For each pair, indicate which conformer is more stable.
Problema 105a,b
What is the configuration of each of the asymmetric centers in the following compounds?
a.
b.
Problema 105c,d
What is the configuration of each of the asymmetric centers in the following compounds?
c.
d.
