Question

Complete the following:

1. Reactant: RCOCl
Reagent: H2 / Pd-BaSO4
Major Product: RCHO
Name of Reaction: Rosenmund Reduction

2. Reactant: CH3COOH
Reagent: Cl2 / Red P
Major Product: Cl-CH2COOH
Name of Reaction: HVZ Reaction

3. Reactant: CH3CHO
Reagent: Zn-Hg / conc. HCl
Major Product: CH3CH3
Name of Reaction: Clemmensen Reduction

Hint:

Important Named Reactions: Rosenmund Reduction: Acid chloride → Aldehyde HVZ Reaction: \(\alpha\)-Halogenation of carboxylic acids Clemmensen Reduction: Aldehyde/Ketone → Hydrocarbon These reactions are widely used in organic synthesis to modify functional groups.

Answer 1

Concept:
Several named reactions are used in organic chemistry to convert functional groups into other useful compounds. The given reactions represent important transformations of carboxylic acid derivatives and carbonyl compounds.

Step 1: Rosenmund Reduction.
In this reaction, an acid chloride is reduced to an aldehyde using hydrogen gas in the presence of a poisoned palladium catalyst (Pd/BaSO4).

RCOCl → RCHO (H2, Pd/BaSO4)

Step 2: Hell–Volhard–Zelinsky (HVZ) Reaction.
Carboxylic acids containing an alpha-hydrogen react with chlorine in the presence of red phosphorus to form alpha-halogenated carboxylic acids.

CH3COOH → Cl-CH2COOH (Cl2 / Red P)

Step 3: Clemmensen Reduction.
In this reaction, aldehydes or ketones are reduced to hydrocarbons using zinc amalgam (Zn-Hg) and concentrated hydrochloric acid.

CH3CHO → CH3CH3 (Zn-Hg / conc. HCl)