Hofmann elimination

Common card · No. 488139

Hofmann elimination is an elimination reaction of an amine to form alkenes. The least stable alkene (the one with the fewest substituents on the carbons of the double bond), called the Hofmann product, is formed. This tendency, known as the Hofmann alkene synthesis rule, is in contrast to usual elimination reactions, where Zaitsev's rule predicts the formation of the most stable alkene. It is named after its discoverer, August Wilhelm von Hofmann. The reaction starts with the formation of a quaternary ammonium iodide salt by treatment of the amine with excess methyl iodide (exhaustive methylation), followed by treatment with silver oxide and water to form a quaternary ammonium hydroxide. When this salt is decomposed by heat, the Hofmann product is preferentially formed due to the steric bulk of the leaving group causing the hydroxide to abstract the more easily accessible hydrogen. In the Hofmann elimination, the least substituted alkene is typically favored due to intramolecular steric...

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