Question

Which statement correctly contrasts Clemmensen and Wolff-Kishner reductions?

• A. Clemmensen uses base, Wolff-Kishner uses acid
• B. Both are done under acidic conditions
• C. Clemmensen is for compounds stable in acid and uses Zn-Hg/HCl; Wolff-Kishner is for those stable in base and uses hydrazine/KOH
• D. Both only reduce carboxylic acids

Hint:

Clemmensen reduction is used under acidic conditions with Zn-Hg/HCl, while Wolff-Kishner is used under basic conditions with hydrazine/KOH.

Answer 1

The Correct Option is C

These two reductions exist as complementary options because some carbonyl compounds break down in acid and others break down in base. Clemmensen reduction is the acid route, zinc amalgam with hydrochloric acid, for substrates that hold up under acidic conditions. Wolff-Kishner reduction is the base route, hydrazine with potassium hydroxide and heat, for substrates that hold up under basic conditions. That acid-versus-base contrast is exactly what option (C) describes.