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Reduction of Carbonyl Groups to Methylene Groups

Clemmensen Reduction: Introduction

Reaction principle

Aldehydes and ketones are reduced to the corresponding methylene groups by treatment with concentrated hydrochloric acid and amalgamated zinc. The mechansm of the reaction is not well understood. Simple alcohols are not reduced under these conditions, giving rise to the opinion that the corresponding alcohols are not intermediates in the reaction.


Reduction of vanillin to creosol (yield 60-67%).

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