The difference between syn and anti addition refers to the orientation of atoms or groups that are added across a double or triple bond in a molecule:
1. Syn Addition
- Both atoms or groups add to the same side (or face) of the double bond.
- This makes the product have both new groups on the same side of the molecule.
- Example processes: hydrogenation with a metal catalyst, hydroboration-oxidation.
2. Anti Addition
- The atoms or groups add to opposite sides (or opposite faces) of the double bond.
- This makes the product have the new groups on opposite sides of the molecule.
- Example processes: halogenation (like Brâ‚‚ addition), epoxidation followed by ring opening.
Key Point
- Syn = same side
- Anti = opposite sides
- The type of addition affects the stereochemistry of the product.