Question

What are Mechanism for the Clemmensen Reduction?

Answer

Here is a proposed mechanism for the Clemmensen reduction: (i) The first step involves the reaction of zinc with hydrochloric acid to form zinc chloride (ZnCl₂) and hydrogen gas (H₂). (ii) After the formation of the organozinc intermediate, the reaction mixture is usually subjected to acidic work-up. (iii) This involves the addition of aqueous acid (such as hydrochloric acid) to the reaction mixture. (iv) In the final step, the organozinc intermediate undergoes reduction and elimination. (v) The zinc atom donates a pair of electrons to the carbonyl carbon, resulting in the formation of a methylene group (CH₂) and regeneration of zinc chloride.