All Study Guides/Chemical and Physical Foundations of Biological Systems

Organic Chemistry: Reactions & Mechanisms

Free MCAT study guide — Chemical and Physical Foundations of Biological Systems

Substitution Reactions

SN1 vs SN2 mechanisms
SN1 vs SN2 mechanisms
FactorSN1SN2
Rate lawrate = k[substrate]rate = k[sub][nuc]
Mechanism2-step, carbocation1-step, concerted
Substrate3° > 2°CH₃ > 1° > 2°
NucleophileWeak (doesn't matter)Strong, unhindered
SolventPolar proticPolar aprotic
StereochemistryRacemizationInversion (Walden)

Elimination Reactions

E1 vs E2 mechanisms
E1 vs E2 mechanisms
Key Point: Strong base + 3° substrate → E2. Weak base + 3° → E1/SN1. Strong nuc + 1° → SN2.

Carbonyl Chemistry

Nucleophilic Acyl Substitution mechanism
Nucleophilic Acyl Substitution (Addition-Elimination)
Fischer Esterification mechanism
Fischer Esterification
Saponification mechanism
Saponification (Base Hydrolysis)
Grignard Reaction mechanism
Grignard Reaction
Aldol Reaction mechanism
Aldol Reaction
Claisen Condensation mechanism
Claisen Condensation

Reactivity order (most to least reactive):

Acid chloride > Anhydride > Ester ≈ Thioester > Amide

Key Point: More resonance stabilization of the carbonyl = less reactive. Amides are least reactive due to N lone pair donation.

Spectroscopy Quick Reference

¹H NMR Chemical Shifts

¹H NMR chemical shift ranges
¹H NMR chemical shift ranges

IR Key Absorptions

IR absorption frequencies
IR absorption frequencies

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