This reduction reaction is known as:

Solution

Chemistry ma’am · 3 steps

Acid chloride in, aldehyde out, with H₂ on poisoned palladium: that combination is Rosenmund.

1. Read the reaction. Benzoyl chloride, C₆H₅COCl, becomes benzaldehyde, C₆H₅CHO. The C-Cl bond is replaced by C-H, and the C=O stays.

   C₆H₅COCl + H₂ →(Pd-BaSO₄) C₆H₅CHO + HCl

2. Why poison the catalyst. BaSO₄ partly deactivates the palladium. The catalyst is then strong enough to break the C-Cl bond but too weak to reduce the aldehyde further to an alcohol, so the reaction stops at CHO.

   Reaction	Starting material	Reagent	Product
   Wolff-Kishner	aldehyde or ketone	NH₂NH₂, then KOH, heat	alkane (C=O → CH₂)
   Etard	toluene	CrO₂Cl₂, then H₃O⁺	benzaldehyde (an oxidation)
   Stephen	nitrile	SnCl₂ + HCl, then H₃O⁺	aldehyde
   Rosenmund	acid chloride	H₂, Pd-BaSO₄	aldehyde

3. So. Only Rosenmund matches an acid chloride reduced by H₂ over Pd-BaSO₄. The answer is (d).

The idea to keep. To name a reaction, match the starting material with the reagent. Acid chloride with H₂/Pd-BaSO₄ is Rosenmund. Nitrile with SnCl₂/HCl is Stephen. Toluene with CrO₂Cl₂ is Etard.

Answer from the NTA final answer key. Solution by PrepWiser.