Ochem 301: Ch 4 problems. read definitions first
3
How many asymmetric centers are present in the compound shown below?
E
Which of the following is capable of exhibiting cis-trans isomerism? A. 1-butene B. 1-pentene C. cyclohexene D. ethene E. 2-butene
1: Z 2: Z
Assign E or Z configuration to these.
1r, 2s
Assign the absolute configuration to the labeled carbon atoms in the following structures.
d
Identify the pair of compounds: A. identical B. conformation isomers C. constitutional isomers D. configurational isomers E. None of these
b
Two products that are stereoisomers are obtained in the reaction of HBr with (S)-4-bromo-1-pentene. What are the configurations of these products? A. (S,S)-2,4-dibromopentane and (R,R)-2,4-dibromopentane B. (S,S)-2,4-dibromopentane and (R,S)-2,4-dibromopentane C. (R,R)-2,4-dibromopentane and (R,S)-2,4-dibromopentane D. both products are (S,R)-2,4-dibromopentanes
e
What is not true of enantiomers? A. They have the same melting point. B. They have the same boiling point. C. They have the same chemical reactivity with non-chiral reagents. D. They have the same density. E. They have the same specific rotation.
b
What is the relationship between the compounds? A. enantiomers B. diastereomers C. constitutional isomers D. conformational isomers E. identical compounds
e
What is the relationship between the following compounds? A. enantiomers B. diastereomers C. constitutional isomers D. conformational isomers E. identical compounds
A
What is the relationship between the following compounds? A. constitutional isomers B. enantiomers C. diastereomers D. conformational isomers E. not isomers
a
What is the relationship between the following compounds? A. constitutional isomers B. enantiomers C. diastereomers D. conformational isomers E. superimposable without bond rotation
identical
What is the relationship between these compounds?
a
Which is the most stable conformation for cis-1-ethyl-3-methylcyclohexane?
D
Which of the following cannot exhibit chirality? A. 2, 3-dibromobutane B. 1, 3-dibromobutane C. 1, 2-dichlorobutane D. 1, 4-dibromobutane E. 1-bromo-2-chlorobutane
2,3
Which of the following compounds are chiral?
3
Which of the following compounds has an asymmetric center?
C
Which of the following describes the most stable conformation of trans-1-tert-butyl-3-methylcyclohexane? A. Both groups are equatorial. B. Both groups are axial. C. The tert-butyl group is equatorial. D. The tert-butyl group is axial and the methyl group is equatorial. E. none of the above
C
Which of the following has two equatorial alkyl substituents in its most stable conformation? A. 1,1-dimethylcyclohexane B. cis-1,2-dimethylcyclohexane C. cis-1,3-diethylcyclohexane D. cis-1,4-diethylcyclohexane E. all of the above
3
Which of the following is a meso compound?
A
Which of the following is the most stable staggered conformation for rotation about the C2-C3 bond in 3-methylpentane?
e
Which of the following is/are optically inactive? A. a 50-50 mixture of R and S enantiomers B. a meso compound C. every achiral compound D. a racemic mixture E. all of the above
d
Which of the following statements correctly describes the molecule shown below? A. It is achiral. B. It is meso. C. Its asymmetric center possesses the S configuration. D. The mirror image of this molecule is its enantiomer. E. The molecule possesses enantiotopic hydrogens.
