Stereochemistry Flashcards
What is stereochemistry?
The branch of chemistry that deals with the spatial arrangements of atoms in molecules and how these arrangements affect the chemical and physical properties of substances.
What are the pharmacological differences between enantiomers?
- Identical efficacy and toxicity
- Same therapeutic and toxic effects but different magnitudes of effect
- One enantiomer may be biologically active while the other is inactive
- Different therapeutic and toxic effects for both enantiomers
Which configuration of chloramphenicol is significant for activity?
R,R-absolute configuration
What is thalidomide and what issue arose from its use?
A chiral molecule used to treat anxiety and morning sickness that led to tragic birth defects due to one enantiomer being effective and safe while the other was not.
What is structural isomerism?
Same molecular formula but different structural formulas.
What is stereoisomerism?
Molecules with the same molecular formula but different spatial arrangements.
What is geometrical isomerism?
Occurs due to restricted rotation around C=C double bonds, resulting in cis and trans forms.
What is optical isomerism?
Occurs when molecules have chiral centers, leading to non-superimposable mirror images.
What is chain isomerism?
Different arrangements of carbon chains.
What is position isomerism?
Same functional group in different positions.
What is functional group isomerism?
Different functional groups with the same molecular formula.
What distinguishes cis and trans forms in geometrical isomerism?
- Cis: Groups/atoms on the same side of the double bond
- Trans: Groups/atoms on opposite sides of the double bond
What criteria must be met to determine geometrical isomerism?
Check for two different atoms/groups attached to each carbon of the double bond.
What is the E/Z nomenclature system?
A system recommended by IUPAC for designating geometric isomerism based on the priority of groups attached to each vinyl carbon.
What are the steps for assigning priorities in the E/Z nomenclature system?
- Rank atoms directly attached to each carbon by decreasing atomic number
- If the first atoms are the same, move to the next atoms until a difference is found
- Double bonds are treated as equivalent to the same number of single bonds
What is optical activity?
The ability of a compound to rotate plane-polarized light.
What does a polarimeter measure?
The rotation of plane-polarized light by optically active substances.
What are the two types of optical rotation?
- Dextrorotatory (right)
- Laevorotatory (left)
What is racemization?
The process of forming a racemic mixture from an enantiomerically pure compound.
What are diastereoisomers?
Stereoisomers that are not enantiomers; they exhibit different physicochemical properties.
Who was Emil Fischer and what did he contribute to chemistry?
Awarded the Nobel Prize in Chemistry in 1902 for his work on the synthesis of sugars and purines.
What is the first step in naming Fischer projections?
Identify the longest carbon chain and number from top to bottom.
What does the D or L configuration indicate in Fischer projections?
The position of the OH group on the chiral carbon farthest from the most oxidized carbon.
What is the significance of the penultimate carbon in Fischer projections?
It is used to determine the D or L configuration based on the position of the OH group.
What is the classification of D-Glucose?
D-Aldohexose
What are the steps to fully name a molecule in Fischer projections?
- Identify the D/L configuration
- Classify as Aldose or Ketose
- State the number of carbons
- Use R/S for absolute configuration if needed
