Hofmann Elimination

R3N(CH3)+ + OH− → alkene + R3N + H2O

Aperçu

The Hofmann elimination converts a quaternary ammonium salt to an alkene, amine, and water upon heating with base. Unlike E2 elimination, Hofmann elimination favors the less substituted alkene (anti-Zaitsev). This reaction was historically used to determine amine structures by exhaustive methylation and elimination.

Participants

Rôle Substance Coefficient État
Produit Water H₂O 1 (l)

Exemple du quotidien

Hofmann elimination was crucial in determining the structures of complex alkaloids like morphine and quinine before modern spectroscopy.

Importance industrielle

While largely replaced by spectroscopic methods for structure determination, Hofmann elimination is still useful in synthetic chemistry for specific alkene preparations.

Propriétés

Type
Organic
Réversible
Non
Énergie
Exothermique
ΔH
-40,0 kJ/mol
Catalyseur
Ag₂O (for quaternary salt formation)

Réactions associées

Epoxidation of Alkenes (mCPBA) Swern Oxidation Oxidation of Secondary Alcohol to Ketone E2 Elimination (Dehydrohalogenation) Claisen Condensation (Ethyl Acetate) Aldol Condensation of Acetaldehyde Kolbe Electrolysis Baeyer-Villiger Oxidation Beckmann Rearrangement (Cyclohexanone Oxime) Dehydration of Ethanol

Frequently Asked Questions

What is the equation for Hofmann Elimination?
The balanced equation is: R₃N(CH₃)⁺ + OH⁻ → alkene + R₃N + H₂O.
What type of reaction is Hofmann Elimination?
Hofmann Elimination is a organic reaction.
Is Hofmann Elimination exothermic or endothermic?
Hofmann Elimination is exothermic (releases energy). The enthalpy change (ΔH) is -40.0 kJ/mol.
What conditions are needed for Hofmann Elimination?
This reaction requires a catalyst (Ag₂O (for quaternary salt formation)).