Clemmensen Reduction

Overall Reaction:

$$\text{R--CO--R'} + 4[\text{H}] \xrightarrow{\text{Zn--Hg / Conc. HCl}, \, \Delta} \text{R--CH}_2\text{--R'} + \text{H}_2\text{O}$$

Concept: Direct deoxygenation of an aldehyde or ketone into its corresponding alkane framework using an acidic zinc amalgam system. Because the reaction runs under highly acidic conditions, it is strictly sensitive to and cannot be used with acid-labile groups (like alcohols or ethers that dehydrate or split).

Notation:

• $$\text{Zn-Hg}$$ = Zinc amalgam;
• $$\text{>CH}_2$$ = Methylene group