Organic · Reaction Mechanisms
Substitution & Elimination (SN1, SN2, E1, E2)
Exam-focused revision notes on Substitution & Elimination (SN1, SN2, E1, E2) for CSIR-NET Chemical Sciences, GATE Chemistry and IIT-JAM — the core concepts, the formulas worth memorising, the traps that cost marks, and a quick-recall table.
The core idea
A leaving group departs from an sp3 carbon. A nucleophile can take its place (substitution) or a base can pull off a β-hydrogen to form a π bond (elimination). Whether the mechanism is concerted or stepwise decides everything.
What this note covers
- 1The core idea
- 2SN2 — bimolecular substitution
- 3SN1 — unimolecular substitution
- 4E2 — bimolecular elimination
- 5E1 — unimolecular elimination
- 6Choosing the pathway (competition)
- 7Common traps students miss
- 830-second recall table
Read the full note
The remaining 7 sections — including the worked examples, the common-traps list and the quick-recall table — are part of ChemVidya Full Access, along with 6,000+ practice questions.
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