Octet

Octet / Reactions

Hofmann Elimination

Hofmann Elimination (E2 Elimination.) Converts CC(C)C[N+](C)(C)C to C=CC(C)C using Ag₂O/H₂O then heat, NaOH, heat. Conditions: Heat.

Elimination

Reaction details

Name

Hofmann Elimination

Type

Elimination

Subtype

E2

Starting Material

CC(C)C[N+](C)(C)C

Product

C=CC(C)C

Reagents

  • Ag₂O/H₂O then heat

  • NaOH, heat

Conditions

Heat

Mechanism
  1. Smiles

    CC(C)C[N+](C)(C)C

    Description

    Quaternary ammonium salt (from amine + excess MeI)

  2. Smiles

    C=CC(C)C

    Description

    E2 elimination gives less substituted alkene

Regiochemistry

Hofmann: less substituted alkene (opposite of Zaitsev)

Tips

  1. Quaternary ammonium is good leaving group

  2. Bulky leaving group forces abstraction from less hindered position

  3. Historical method for determining amine structure

Related Reactions

  • e2-elimination

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Reactions

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Source collection

SN2 with Hydroxide

SN2 with Hydroxide (SN2 Substitution.) Converts CCBr to CCO using NaOH, KOH. Conditions: Polar aprotic solvent in DMSO, DMF, or acetone. Stereochemistry: Inversion of configuration (Walden inversion).

Substitution

SN2 with Cyanide

SN2 with Cyanide (SN2 Substitution.) Converts CCI to CC#N using NaCN, KCN. Conditions: Polar aprotic solvent in DMSO or DMF. Stereochemistry: Inversion of configuration.

Substitution

SN1 Solvolysis

SN1 Solvolysis (SN1 Substitution.) Converts CC(C)(C)Br to CC(C)(C)O using H₂O. Conditions: Polar protic solvent, heat in Water or aqueous ethanol. Stereochemistry: Loss of stereocontrol (planar carbocation attacked from either face → racemization if chiral ce...

Substitution

SN2 with Tosylate Leaving Group

SN2 with Tosylate Leaving Group (SN2 Substitution.) Converts CCOS(=O)(=O)c1ccc(C)cc1 to CCN=[N+]=[N-] using NaN₃. Conditions: Polar aprotic solvent.

Substitution

SN2 with Azide

SN2 with Azide (SN2 Substitution.) Converts CCBr to CCN=[N+]=[N-] using NaN₃. Conditions: Polar aprotic solvent.

Substitution

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..

Elimination

Study guides

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