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Questions and Answers
What tragic consequence was linked to the use of Thalidomide in pregnant women?
What tragic consequence was linked to the use of Thalidomide in pregnant women?
- Development of severe birth defects (correct)
- Enhanced cognitive development in children
- Increased chances of multiple births
- Higher rates of successful pregnancies
Which characteristic indicates that a molecule is non-chiral?
Which characteristic indicates that a molecule is non-chiral?
- Possession of a plane of symmetry (correct)
- Absence of stereoisomers
- Two distinct enantiomers
- Presence of a chiral center
Why is it problematic for enantiomers to share the same IUPAC name?
Why is it problematic for enantiomers to share the same IUPAC name?
- It eliminates the need for distinct drug regulations.
- It complicates the process of drug synthesis.
- It can lead to confusion in clinical settings. (correct)
- It reduces molecular diversity in chemical nomenclature.
What is the main structural feature that differentiates enantiomers?
What is the main structural feature that differentiates enantiomers?
Which enantiomer of Thalidomide is associated with therapeutic effects?
Which enantiomer of Thalidomide is associated with therapeutic effects?
How can a plane of symmetry be defined in a molecule?
How can a plane of symmetry be defined in a molecule?
When was the link between Thalidomide and birth defects discovered?
When was the link between Thalidomide and birth defects discovered?
What is an outcome of all molecules having a plane of symmetry?
What is an outcome of all molecules having a plane of symmetry?
What does the R,S system help in the context of enantiomers?
What does the R,S system help in the context of enantiomers?
What is the first step in assigning the (R) and (S) configurations at a stereocenter?
What is the first step in assigning the (R) and (S) configurations at a stereocenter?
If two atoms directly attached to a chirality center have the same atomic number, what should you do next?
If two atoms directly attached to a chirality center have the same atomic number, what should you do next?
What does a clockwise path from highest to lowest priority indicate at an asymmetric carbon?
What does a clockwise path from highest to lowest priority indicate at an asymmetric carbon?
When determining the priority of groups containing double or triple bonds, how should you assess the atoms involved?
When determining the priority of groups containing double or triple bonds, how should you assess the atoms involved?
What should you do if the lowest priority group is not pointing away from you during configuration assignment?
What should you do if the lowest priority group is not pointing away from you during configuration assignment?
What would be an appropriate action if two groups attached to a stereocenter have the same atomic number and are linked to another set of atoms?
What would be an appropriate action if two groups attached to a stereocenter have the same atomic number and are linked to another set of atoms?
Which of the following is the correct order of operations when assigning (R) and (S) configurations?
Which of the following is the correct order of operations when assigning (R) and (S) configurations?
Which configuration corresponds to a counter-clockwise path tracing from highest to lowest priority?
Which configuration corresponds to a counter-clockwise path tracing from highest to lowest priority?
After determining a molecule's configuration, what should you confirm regarding the bonded atoms?
After determining a molecule's configuration, what should you confirm regarding the bonded atoms?
In the example of (2-Butanol), which of the following configurations is indicated if the path is clockwise?
In the example of (2-Butanol), which of the following configurations is indicated if the path is clockwise?
Which pairs of compounds are classified as enantiomers?
Which pairs of compounds are classified as enantiomers?
What characteristic prevents compounds III and IV from being classified as enantiomers?
What characteristic prevents compounds III and IV from being classified as enantiomers?
Which statement correctly describes diastereomers among the given compounds?
Which statement correctly describes diastereomers among the given compounds?
What is the relationship between compounds I and III?
What is the relationship between compounds I and III?
Which of the following is a correct full name for a compound with the configuration (2R, 3R)?
Which of the following is a correct full name for a compound with the configuration (2R, 3R)?
What configuration is specified for the C2 chiral center in 2,3-Dibromobutane?
What configuration is specified for the C2 chiral center in 2,3-Dibromobutane?
In naming compounds with multiple chirality centers, which aspect is crucial for determining configurations?
In naming compounds with multiple chirality centers, which aspect is crucial for determining configurations?
How many stereoisomers exist for the given compounds?
How many stereoisomers exist for the given compounds?
Which is true about the configuration of C2 in the compound?
Which is true about the configuration of C2 in the compound?
Which statement accurately describes cis-1,3-dimethylcyclohexane?
Which statement accurately describes cis-1,3-dimethylcyclohexane?
What is true regarding 1,3-dimethylcyclohexane and its stereoisomers?
What is true regarding 1,3-dimethylcyclohexane and its stereoisomers?
How do trans-1,2-dimethylcyclohexane and cis-1,2-dimethylcyclohexane relate to enantiomers?
How do trans-1,2-dimethylcyclohexane and cis-1,2-dimethylcyclohexane relate to enantiomers?
What characteristic distinguishes trans-1,3-dimethylcyclohexane from cis-1,3-dimethylcyclohexane?
What characteristic distinguishes trans-1,3-dimethylcyclohexane from cis-1,3-dimethylcyclohexane?
Which of the following statements about 1,4-dimethylcyclohexane is correct?
Which of the following statements about 1,4-dimethylcyclohexane is correct?
What occurs in the interconversion of (II) and (III) of 1,2-dimethylcyclohexane?
What occurs in the interconversion of (II) and (III) of 1,2-dimethylcyclohexane?
What percentage of enantiomeric excess does an enantiomerically pure sample achieve?
What percentage of enantiomeric excess does an enantiomerically pure sample achieve?
What would be the observed specific rotation of a sample of (S)-(+)-2-butanol containing an equimolar amount of (R)-(–)-2-butanol?
What would be the observed specific rotation of a sample of (S)-(+)-2-butanol containing an equimolar amount of (R)-(–)-2-butanol?
How can enantiomeric excess be calculated from optical rotations?
How can enantiomeric excess be calculated from optical rotations?
If a mixture of (S)-(+)-2-butanol shows a specific rotation of +6.76, what is the specific rotation of a completely racemic mixture?
If a mixture of (S)-(+)-2-butanol shows a specific rotation of +6.76, what is the specific rotation of a completely racemic mixture?
Which of the following statements is true regarding a sample of (S)-(+)-2-butanol that shows a specific rotation between 0 and +13.52?
Which of the following statements is true regarding a sample of (S)-(+)-2-butanol that shows a specific rotation between 0 and +13.52?
Which of the following statements best describes enantiomeric excess (ee)?
Which of the following statements best describes enantiomeric excess (ee)?
In the example, how is the enantiomeric excess of the (S)-(+)–2-butanol calculated when the specific rotation is +6.76?
In the example, how is the enantiomeric excess of the (S)-(+)–2-butanol calculated when the specific rotation is +6.76?
Which statement correctly describes the specific rotation of an enantiomerically pure sample of (S)-(+)–2-butanol?
Which statement correctly describes the specific rotation of an enantiomerically pure sample of (S)-(+)–2-butanol?
What is the specific rotation of the achiral molecules discussed in the synthesis of chiral molecules?
What is the specific rotation of the achiral molecules discussed in the synthesis of chiral molecules?
When a specific rotation of a sample is known, how can one piece together the enantiomeric ratio?
When a specific rotation of a sample is known, how can one piece together the enantiomeric ratio?
Study Notes
Chirality in Drugs
- Thalidomide was used to treat morning sickness in pregnant women, but it was later discovered that it caused serious birth defects.
- Thalidomide is a chiral molecule and its enantiomers have different effects. The (R)- enantiomer is effective in treating morning sickness, while the (S)-enantiomer causes serious birth defects.
Testing for Chirality: Planes of Symmetry
- A molecule is achiral (not chiral) if it possesses a plane of symmetry.
- A plane of symmetry is an imaginary plane that bisects a molecule so that the two halves are identical mirror images.
Naming Enantiomers: The R,S-System
- The R,S-system is used to name enantiomers.
- Rule 1: Assign priorities to the four groups attached to the chirality center based on atomic number, higher atomic number = higher priority.
- Rule 2: If priorities cannot be assigned based on atomic number of the atoms directly attached to the chirality center, then the next set of atoms are examined until a decision can be made.
- Rule 3: Visualize the molecule with the lowest priority group pointing away from you, then trace a path from highest to lowest priority. If the path is clockwise, the configuration is (R); if the path is counterclockwise, the configuration is (S).
- Rule 4: For groups containing double or triple bonds, assign priorities as if both atoms were duplicated or triplicated.
Racemic Forms and Enantiomeric Excess
- An enantiomerically pure sample contains only one enantiomer and has an enantiomeric excess of 100%.
- Enantiomeric excess (ee) is also known as optical purity and can be calculated from the optical rotation of a mixture.
- The formula for enantiomeric excess is:
% enantiomeric excess = (observed specific rotation / specific rotation of the pure enantiomer) x 100
Synthesis of Chiral Molecules
- A racemic mixture is a 50:50 mixture of enantiomers.
- The synthesis of chiral molecules often produces a racemic mixture, but sometimes, a single enantiomer can be obtained through a chiral catalyst.
- If two chiral centers are present, it is possible to have more than two stereoisomers:
- Enantiomers are non-superimposable mirror images.
- Diastereomers are stereoisomers that are not enantiomers.
- Meso compounds are achiral molecules with chiral centers.
Fischer Projection Formulas
- Fischer projection formulas are a way of representing three-dimensional molecules in two dimensions.
- In Fischer projections, horizontal bonds point out of the plane and vertical bonds point into the plane.
- Cyclohexane can exist as cis and trans isomers.
- 1,4-Dimethylcyclohexane does not have a plane of symmetry, and the cis and trans forms are diastereomers.
- 1,3-Dimethylcyclohexane has a plane of symmetry when in the cis conformation and it is a meso compound.
- The trans conformation of 1,3-dimethylcyclohexane has no plane of symmetry and exists as two enantiomers.
- 1,2-Dimethylcyclohexane exists as two enantiomers; both cis and trans configurations result in enantiomers.
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Description
Explore the crucial role of chirality in drug effectiveness, particularly focusing on thalidomide's enantiomers and their contrasting effects. Understand the concepts of achirality, planes of symmetry, and the R,S-system for naming enantiomers. This quiz delves into the complexities of molecular structures that impact pharmacology.
