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

In the Hell-Volhard-Zelinsky reaction, a carboxylic acid bearing an alpha-hydrogen reacts with Cl<sub>2</sub> and red phosphorus to give:

Answer: an alpha-chloro acid.

  • A an alpha-chloro acid
  • B an acyl chloride
  • C an alpha-hydroxy acid
  • D a saturated chloroalkane

Correct answer: A. an alpha-chloro acid

Explanation: The HVZ reaction chlorinates the alpha-carbon, giving an alpha-chlorocarboxylic acid.

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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