page 11 Flashcards
What are enantiomers?
A: Enantiomers are a pair of chiral molecules that are non-superimposable mirror images of each other.
How do you draw the first enantiomer of a chiral molecule?
A: Arbitrarily place the four groups around the stereogenic center in a tetrahedral structure.
How do you draw the second enantiomer of a chiral molecule?
A: Draw the mirror image of the first enantiomer by reflecting all groups across a mirror plane.
Why are enantiomers chiral?
A: They lack a plane of symmetry and have a stereogenic center, making their mirror images non-superimposable.
What is the difference between a chiral molecule and its mirror image?
A: A chiral molecule and its mirror image have the same connectivity but opposite spatial arrangements of atoms around the stereogenic center.
Why is C1 in methylcyclopentane not a stereogenic center?
A: C1 is not a stereogenic center because it is bonded to two identical groups (the rest of the cyclopentane ring), making it lack four different groups.
What is the significance of equivalent groups on rings in determining stereogenic centers?
A: Equivalent groups (e.g., symmetrical parts of a ring) cannot make a carbon a stereogenic center because they violate the rule of having four different groups.
Why is C3 in 3-methylcyclohexene a stereogenic center?
A: C3 is a stereogenic center because it is attached to:
A hydrogen (H).
A methyl group (CH₃).
Two carbons in the ring that are not identical due to the double bond.
How does the presence of a double bond affect stereogenic centers in rings?
A: A double bond in the ring creates asymmetry among carbons, which can make attached carbons like C3 stereogenic.
What is the relationship between ring symmetry and stereogenic centers?
A: Rings with high symmetry are less likely to have stereogenic centers unless the symmetry is broken by substituents or double bonds.
What is thalidomide, and why are its enantiomers significant?
A: Thalidomide is a drug with two enantiomers:
One acts as an anti-nausea drug.
The other is a teratogen, causing severe birth defects.
Why do stereogenic centers matter in thalidomide?
A: The stereogenic centers create enantiomers with vastly different biological effects, highlighting the importance of chirality in drug design.
How do stereogenic centers influence the function of biologically active molecules?
A: Stereogenic centers determine the 3D structure, which directly affects how the molecule interacts with biological targets, like enzymes and receptors.
What is the relationship between chirality and drug activity in thalidomide?
A: The chirality of thalidomide results in one enantiomer being therapeutic, while the other is harmful, emphasizing the need for stereochemical precision in pharmaceuticals.
