CHEM231: Alkenes

incomplete

Regiochemistry

Deals with which position on a molecule a reaction occurs

Markovnikov vs. Anti-Markovnikov

Markovnikov’s Rule

The electrophile (H⁺) adds to the carbon with more hydrogens, placing the nucleophile on the more substituted carbon.

H and C are on the same side (both on the less crowded side).

Anti-Markovnikov

The initial attacker (Br·) adds to the carbon with more hydrogens, ultimately placing the H on the more substituted carbon.

Br and C are on the same side (both on the less crowded side).

Stereochemistry

Deals with the three-dimensional arrangement of atoms in space

Syn vs. Anti Addition

Rearrangements happen when…

1. when a 2° or 3° carbocation is on the position just outside of 3; 4 or 5-membered ring → EXPANSION

2. when a 2° carbocation is next to 3° center → HYDRIDE SHIFT

3. when a 2° carbocation is next to 4° center w/ CH₃ group → METHYL SHIFT