Stereochemistry Lecture 1: Introduction to Stereochemistry

Stereochemistry

• Stereochemistry is the field of organic chemistry that aims to understand the relative spatial arrangement of atoms in molecules.
• It focuses on deducing the 3-D structure of an atom.

Isomers

• Isomers are molecules with the same molecular formula but different structural or spatial arrangements of atoms.
• This variation can lead to differences in physical or chemical properties.

Types of Isomers

Constitutional Isomers (Structural Isomerism / Skeletal Isomerism)

• They are different molecules with the same formula but connected together differently.
• They cannot be converted into each other without breaking and remaking bonds.
• All physical properties of constitutional isomers are different, including melting points, boiling points, solubility, and densities.

Types of Constitutional Isomers

• Chain isomers: molecules with the same molecular formula but different arrangements of the carbon 'skeleton'.
• Position isomers: different positions of the same functional group in the molecule.
• Functional isomers: different positions of atoms giving different functional groups.

Tautomers

• Tautomers are isomers of a compound that differ only in the position of protons and electrons.
• The carbon skeleton of the compound remains unchanged.
• Tautomerism involves a simple proton transfer in an intramolecular fashion, often acid or base catalyzed.

Keto-Enol Tautomerism

• A common process in which the 'keto' form is typically more stable, but in some instances, the 'enol' form can be more stable.

Metamerism

• Compounds having the same molecular formula but different numbers of carbon atoms (alkyl groups) on either side of a functional group (e.g., -O-, -S-, -NH-, -C(=O)-, esters, amides, etc).

Ring-Chain Isomerism

• Compounds having the same molecular formula but with one having an open chain and the others having cyclic structures.
• This phenomenon is known as ring-chain isomerism.

Explore the basics of stereochemistry, the field of organic chemistry that focuses on the spatial arrangement of atoms in molecules. Learn about isomers, compounds with the same molecular formula but different structures.