Zaymiey

🧪 Chemistry  ·  Aldehydes, Ketones and Carboxylic Acids  ·  NEET & JEE

Which compound gives a yellow precipitate with 2,4-dinitrophenylhydrazine?

Answer: Carbonyl compounds.

  • A Alcohols
  • B Ethers
  • C Carbonyl compounds
  • D Carboxylic acids

Correct answer: C. Carbonyl compounds

Explanation: Carbonyl compounds form coloured 2,4-DNP hydrazones (yellow to orange precipitates).

Nucleophilic Addition to C=ONu:-CORR'CO-RR'Nu

Curved arrows show the nucleophile attacking the carbonyl carbon while the C=O pi electrons move onto oxygen, giving a tetrahedral alkoxide intermediate.

Concept context

Aldehydes, ketones, carboxylic acids, and their derivatives (esters, amides, acid chlorides). Key reactions include nucleophilic addition, Aldol condensation, Cannizzaro, and Claisen. Very heavily tested in JEE and NEET.

Read the full Aldehydes, Ketones and Carboxylic Acids notes →