Octet / Reactions
E2 Elimination
E2 Elimination (E2 Elimination.) Converts CC(Br)CC to CC=CC using KOtBu, NaOEt, NaOH (conc.). Conditions: Strong base, heat in t-BuOH or EtOH. Stereochemistry: Anti-periplanar geometry required. E/Z depends on which H is removed..
Reaction details
E2 Elimination
Elimination
E2
CC(Br)CC
CC=CC
KOtBu
NaOEt
NaOH (conc.)
Strong base, heat
t-BuOH or EtOH
- Smiles
CC(Br)CC
- Description
2-Bromobutane: H and Br must be anti-periplanar
- Smiles
CC(Br)CC
- Description
Base removes β-hydrogen as C=C forms and Br⁻ leaves
- Smiles
CC=CC
- Description
2-Butene formed (E2 is concerted, one step)
Anti-periplanar geometry required. E/Z depends on which H is removed.
Zaitsev: more substituted alkene favored (with most bases)
Rate = k[substrate][base]
Anti-periplanar = H and leaving group on opposite sides, 180°
Bulky bases (KOtBu) favor Hofmann product (less substituted)
Competes with SN2 - base vs nucleophile
e1-elimination
sn2-bromide-hydroxide
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