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(i) Complete the reaction… (Class 12 Chemistry 2023, Q24b)

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ChemistryCBSE Class 12 · Board exam 2023, set 56/5/1 · 2 marks · Very short answer

CBSE Class 12 Chemistry 2023: question 24(b)

Set in the CBSE Class 12 board exam of 2023, paper 56/5/1, section B, question 24(b), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q24(b) · 2 marks · Very short answerAmines

(i) Complete the reaction with the main product formed :
Benzenediazonium chloride ()
(ii) Convert Bromoethane to Propanamine.

Figure in the paper: Benzene ring with N2+ Cl- substituent, followed by reaction arrow with CH3CH2OH above it. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 56/5/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Ethanol acts as a mild reducing agent towards diazonium salts, replacing –N₂⁺ by H.

Hint 2

Propanamine has one carbon more than bromoethane: which nucleophile adds one carbon and can later be reduced to –CH₂NH₂?

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. (i) Ethanol reduces the diazonium salt to benzene:

    Main product: benzene.

    1 mark

  2. (ii) Step-up by one carbon via the nitrile:

    (bromoethane → propanenitrile → propan-1-amine)

    1 mark

Answer: (i) Benzene (with N₂, CH₃CHO, HCl); (ii) CH₃CH₂Br → (KCN) CH₃CH₂CN → (LiAlH₄) CH₃CH₂CH₂NH₂

Where the marks are

  • Correct product benzene in reaction with ethanol (1 mark)
  • Conversion via KCN then reduction to propanamine (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Amines, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 56/5/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.