Chiral Molecules Flashcards
What are chiral drugs?
Drugs that exist in enantiomeric forms, where one enantiomer is active and the other may be inactive or have different effects.
What are the four scenarios regarding enantiomers in chiral drugs?
- Only one enantiomer is active
- Both enantiomers show essentially identical activities
- Both enantiomers have similar activity, but one is more active
- Enantiomers show different pharmacological activities
What is enzymatic resolution?
An enzyme selectively converts one enantiomer in a racemic mixture to another compound, after which the unreacted enantiomer and the new compound are separated.
What is chromatographic resolution?
Chiral high performance liquid chromatography (HPLC) where diastereomeric interactions cause enantiomers to move at different rates through a stationary phase.
How can a racemic mixture be resolved via diastereomer formation?
By reacting a racemic mixture with a single enantiomer of another compound, yielding a mixture of diastereomers that can be separated.
What are the properties of diastereomers that allow their separation?
- Different melting points
- Different boiling points
- Different solubilities
Why do conventional methods fail to separate enantiomers?
Enantiomers have identical solubilities in ordinary solvents and identical boiling points.
Who first separated a racemic form of a salt of tartaric acid?
Pasteur in 1848.
Which enantiomer of Naproxen is active?
(S) enantiomer.
What happens to the (R) enantiomer of Naproxen in the body?
It is slowly converted to the (S) enantiomer.
What is a characteristic of (S)-Penicillamine?
The (S) isomer is a highly potent therapeutic agent for primary chronic arthritis, while the (R) enantiomer is toxic.
What are carbohydrates?
A group of polyhydroxy aldehydes, ketones, or acids, or their derivatives, generally in the form CnH2nOn or Cn(H2O)n.
How are monosaccharides classified based on carbon atoms?
- Triose - 3 carbon atoms
- Tetrose - 4 carbon atoms
- Pentose - 5 carbon atoms
- Hexose - 6 carbon atoms
What is the structure of disaccharides?
Disaccharides contain a glycosidic acetal bond between the anomeric carbon of one sugar and an –OH group of another sugar.
What is the difference between enantiomers and diastereomers?
Enantiomers are mirror images of each other, while diastereomers are not.
What is a meso compound?
A non-optically active member of a set of stereoisomers that contains stereogenic centers but is superposable on its mirror image.
What is enantioselective synthesis?
A reaction that produces one enantiomer predominantly over its mirror image, influenced by a chiral reagent, catalyst, or solvent.
What happens when hyoscyamine is heated with dilute base?
It racemizes, leading to a solution that becomes optically inactive.
What is the role of enzymes in organic reactions?
Enzymes are biological catalysts that increase reaction rates and assert chiral influence, binding reactants at a chiral active site.
What are Fischer projections used for?
They are useful for representing molecules with several chiral centers, such as sugars.
What are glycosides?
The products formed when the cyclic hemiacetal or hemiketal forms of monosaccharides react with alcohol.
What is a common glycosidic bond in disaccharides?
A bond between C-1 of the first sugar and the –OH at C-4 of the second sugar, called a 1,4’-link.
What is the stereochemical relationship between D-galactose and D-glucose?
They are epimers, differing at one stereogenic center.
What occurs during the cyclization of monosaccharides?
Intramolecular nucleophilic addition reaction leads to the formation of a cyclic hemiacetal or hemiketal.
