Organic Chemistry for the MCAT

Functional Groups

Key functional groups to know:

• Hydroxyl (-OH): Alcohols
• Carbonyl (C=O): Aldehydes and ketones
• Carboxyl (-COOH): Carboxylic acids
• Amino (-NH₂): Amines
• Thiol (-SH): Thiols

Stereochemistry

A chiral center has four different substituents. Assign R/S using Cahn-Ingold-Prelog priority rules.

• Enantiomers: Non-superimposable mirror images (same physical properties, opposite optical rotation)
• Diastereomers: Stereoisomers that are NOT mirror images (different physical properties)

Substitution & Elimination

| Reaction | Steps | Favored By | |----------|-------|------------| | SN1 | 2 (carbocation) | 3° substrate, polar protic solvent | | SN2 | 1 (backside attack) | 1° substrate, strong nucleophile | | E1 | 2 (carbocation) | 3° substrate, heat | | E2 | 1 (anti-periplanar) | Strong base, heat |

Spectroscopy

• IR: O-H ~3300 cm⁻¹ (broad), C=O ~1700 cm⁻¹ (sharp)
• ¹H NMR: Chemical shift reflects electronic environment; splitting follows n+1 rule
• Mass Spec: Molecular ion peak gives molecular weight