Concept:Analytical tests for carbonyl compounds take advantage of either oxidation-reduction chemistry or nucleophilic addition-elimination reactions.
Solution:- The 2,4-dinitrophenylhydrazine (2,4-DNPH) test targets the carbonyl group (\( C=O \)) directly.
- Since both aldehydes and ketones contain a carbonyl group, both readily undergo condensation with 2,4-DNPH to form a yellow, orange, or red precipitate of a hydrazone.
- Therefore, this test is a universal indicator for the presence of aldehydes and ketones.
Why other options are incorrect:The Silver mirror (Tollens'), Fehling's, and Benedict's tests are mild oxidation reactions. Aldehydes are easily oxidized, so they give positive results. Ketones resist mild oxidation, yielding negative results.
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