All GRE Subject Test: Chemistry Resources
Example Questions
Example Question #111 : Organic Chemistry, Biochemistry, And Metabolism
The molecules shown below are best described as __________.
epimers
enantiomers
isomers
diastereomers
isomers
The molecules in this problem are isomers because they each have unique configurations and do not share the same funcitonal groups at the same carbon positions. Enantiomers are reflections of each other. Diastereomers are stereoisomers that differ at one or more stereocenters, while epimers are stereoisomers that differ at only one stereocenter.
Example Question #1 : Stereochemistry
Which of the following is not a geometric isomer of pentene?
All of these are geometric isomers of pentene.
Geometric isomers are compounds that have the same molecular formula but they differ in the way they are arranged spatially. Pentene carries the molecular formula, . The longest chain of carbon atoms should be five carbons. According to its name, pentene is an alkene due to the -ene form its name, therefore must also contain a
bond. The only compound without a chain of 5 carbons consecutively is
and this compound is not a geometric isomer of pentene.
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All GRE Subject Test: Chemistry Resources
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