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Is chloroethane chiral or achiral?
Achiral (neither C atom has 4 different groups attached)
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How many stereoisomers of 2-bromo-3-chloropentane are possible?
4 (2 chiral centers; 2 n stereoisomers)
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How are the compounds (1S,2R)-2-methylcyclohexanol and (1S,2S)-2-methylcyclohexanol related? Are they enantiomers or diastereomers?
Diastereomers
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What is a meso compound?
A molecule containing chiral centers but which is achiral due to an internal plane of symmetry
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Name the following molecule, including stereocenters
(1R,3S)-1-bromo-3-fluorocyclohexane
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How many stereoisomers of the following molecule are possible?
4 (there are only 2 chiral centers)
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Define absolute configuration
The actual 3-dimensional arrangement of atoms about a chiral center
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Why is sp3 N usually not chiral?
N undergoes the process of pyramidal inversion
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Give the following molecule a complete IUPAC name (including stereocenters):
(2S,3S,4R)-4-bromo-3-isopropylpentan-2-ol
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How many chiral centers does the following molecule possess?
5
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Why are enantiomers difficult to separate?
They have the same physical properties, e.g. melting point, boiling point, and retention factor in chromatography
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What is the optical rotation observed for (2R,3S)-butane-2,3-diol?
Rotation will be 0 since the molecule is meso (internal plane of symmetry)
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If the specific optical rotation observed for (+)-2-butanol is +13.5o, what is the expected specific rotation of its enantiomer?
-13.5o since enantiomers have equal, but opposite, rotations
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Is it possible to physically separate diastereomers?
Yes; the will have different physical properties such as boiling point and chromatographic retention factors
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Label the stereocenters in the following molecule as having either the R or S configuration.
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How many possible stereoisomers are there for a molecule with 4 stereocenters?
16 (2n = 24)
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What is the expected optical rotation of trans-2-butene?
Zero; planar alkenes do not typically exhibit asymmetry
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How many stereoisomers would epoxidation of trans-2-pentene produce?
2; syn addition leads to two of the possible 4 stereo isomers (stereochemistry of double bond is carried through since addition is concerted):
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How many different stereiosomers are possible for 2,3-dibromobutane?
3; two of the expected 4 isomers will be meso and therefore equivalent:
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How many stereoisomers are possible for 2-bromo-3-methylbutane?
2; only one chiral center:
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