How do you determine if a mono-substituted cycloalkane is chiral?
If there is a plane of symmetry, the structure of achiral. If there is no plane of symmetry, the structure is chiral (also applies to disubstituted cycloalkanes)
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Describe the positions of Br and Cl in the two extreme conformations for the Z configuration
Either Br equatorial and Cl axial or Br axial and Cl equatorial
2 of 9
Describe the positions of Br and Cl in the two extreme conformations for the E configuration
Br and Cl equatorial or Br and Cl axial
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Can the methyl substituent in methylcyclohexane be either equatorial or axial?
Yes (also methyl substituent rotating getting close to other axial H substituents)
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Why is the equatorial conformer favoured?
There is 1,3-diaxial interaction. Equatorial conformer minimizes steric crowding and 1,3-diaxial interaction (e.g. diaxial interaction: 2-methyl-2-cyclohexylpropane)
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Describe the synthesis of racemates (3)
Hydrogenation of ketones. Hydrogen attacks from both sides. Equimolar mixture of enantiomers (e.g R and S configuration)
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Why are enantiomers difficult to separate?
They have identical chemical properties (need to convert to diastereomers/have different properties and then separate/regenerate enantiomers)
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Describe the resolution process
To separate R and S enantiomers, react with optically pure R/S. Prepare mixture of diastereomers (separation/distillation). Prepare pure enantiomers by doing the reverse of the first reaction
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SN1, SN2, Elimination etc
See lecture slides
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Other cards in this set
Card 2
Front
Describe the positions of Br and Cl in the two extreme conformations for the Z configuration
Back
Either Br equatorial and Cl axial or Br axial and Cl equatorial
Card 3
Front
Describe the positions of Br and Cl in the two extreme conformations for the E configuration
Back
Card 4
Front
Can the methyl substituent in methylcyclohexane be either equatorial or axial?
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