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Common Reactions

Note: This is a high-level conceptual overview.

Comparison Summary

SN1: Tertiary substrates, weak nucleophiles, polar protic solvents.
SN2: Primary substrates, strong nucleophiles, polar aprotic solvents.
E1: Competes with SN1 (often Favored by heat).
E2: Strong base, requires anti-periplanar geometry.

Substitution Reactions

SN1

Unimolecular Nucleophilic Substitution. Occurs in two steps. The leaving group leaves, forming a carbocation, then the nucleophile attacks. Rate depends on substrate concentration only.

SN2

Bimolecular Nucleophilic Substitution. Occurs in one step. The nucleophile attacks at the same time the leaving group leaves (backside attack). Rate depends on both substrate and nucleophile.

Elimination Reactions

Reactions where elements of the starting material are "lost" and a pi bond (double bond) is formed.

E1 vs E2

Similar to SN1/SN2, E1 involves a carbocation intermediate (2 steps), while E2 is a concerted single step. E2 typically requires a strong base.

What Determines the Reaction?

1. Substrate

Primary (SN2/E2) vs Tertiary (SN1/E1).

2. Nucleophile/Base

Strong (SN2/E2) vs Weak (SN1/E1).

3. Solvent

Polar Protic (SN1) vs Polar Aprotic (SN2).

4. Temperature

Heat generally favors Elimination over Substitution.

Note: Detailed mechanisms and arrow-pushing are typically covered in later organic chemistry courses.

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