Stereochemistry and Chirality

Introduction to Stereochemistry

• Transition from conformational level to configurational level.
• Focus on chirality as a key property in stereochemistry.
• Explore relationships between molecules and types of isomerism.

Chirality and Stereocenters

• Chirality: A property of objects indicating handedness.
• Examples of chirality in everyday objects (e.g., right-handed and left-handed screws).
• Criteria for determining if a molecule is chiral.
• Stereocenter: Important structural unit associated with chirality.

Importance of Chirality

• Historical Context: Thalidomide case.
  • Thalidomide used for morning sickness.
  • Mixture of two enantiomers generated in the body; one is beneficial, the other causes birth defects.
• Ignoring chirality can have serious consequences in drug development.
• Biochemistry is predominantly chiral chemistry; understanding spatial orientations is essential.

Examples of Chiral Biochemical Molecules

• Small Molecule Level: Glucose (chiral sugar).
• Polymeric Level: Amylose polymer formed from glucose.
• DNA Structure: Double helix with chirality in monomers (e.g., adenosine).
• Amino Acids: Example with tryptophan as part of chiral proteins.

Fascination with Stereochemistry

• Intrinsic interest in spatial properties of molecules.
• Connections between molecular stereochemistry and everyday objects.
• Enantiomeric relationships observed in human hands.

Difference Between Enantiomers

• Enantiomers: Subtle differences yet identical in many interactions.
• Example: Ambidextrous use of a spoon; no handedness.
• Contrast with a handed object (e.g., coffee mug):
  • Interaction differs based on which hand is used.
  • Importance of handedness in practical scenarios.

Conclusion

• Upcoming videos will elaborate on formalizing these concepts at the molecular level.