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

Acetaldehyde on treatment with excess ethanol and dry HCl gives:

Answer: Acetal.

  • A Acetal
  • B Hemiacetal
  • C Acetone
  • D Formic acid

Correct answer: A. Acetal

Explanation: Two moles of alcohol react with one aldehyde in presence of HCl to form acetal (1,1-diethoxyethane).

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.

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