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MHT CET202521 Apr 2025Morning ShiftChemistryAldehydes and KetonesActual

Identify the reagent ' R ' used in the following reaction. Ketone R Semicarbazone

Options

  1. ANH ₂ OH
  2. BNH ₂- NH - CONH ₂
  3. CNH ₂- NH - C ₆ H ₅
  4. DNH ₂- NH ₂

Correct answer

B. NH ₂- NH - CONH ₂

Step-by-step solution

Semicarbazones are formed when ketones or aldehydes react with semicarbazide. The reaction proceeds as R₂ C=O + NH₂ -NH-CONH₂ [H^+] R₂ C=N-NH-CONH₂ + H₂ O . Among the options, hydroxylamine ( NH₂ OH ) produces oximes, phenylhydrazine ( NH₂ -NH-C₆ H₅ ) forms phenylhydrazones, and hydrazine ( NH₂ -NH₂ ) yields hydrazones. Only semicarbazide ( NH₂ -NH-CONH₂ ) gives the semicarbazone product.

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