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Organic conversion

Aniline to p-bromoaniline

3 steps: substitution, then substitution, then hydrolysis

Class 12, Chapter 9 Amines

  1. NH2
    AnilineC₆H₅NH₂Amine
  2. Step 1

    CH₃COCl, pyridine

    i

    Acetylation protects the NH₂ group and lowers its activating power; the base takes up the HCl.

    Also written: (CH₃CO)₂O, pyridine

    OHN
    AcetanilideC₆H₅NHCOCH₃Amide
  3. Step 2

    Br₂, CH₃COOH

    i

    The acetyl group tames the NH₂ so only one bromine enters, mainly para.

    OHNBr
    p-Bromoacetanilidep-BrC₆H₄NHCOCH₃Amide
  4. Step 3

    H₃O⁺, heat

    i

    Hydrolysis removes the protecting acetyl group.

    NH2Br
    p-Bromoanilinep-BrC₆H₄NH₂Amine

Exam answer

  1. Step 1: Aniline to acetanilide: CH₃COCl, pyridine.
  2. Step 2: Acetanilide to p-bromoacetanilide: Br₂, CH₃COOH.
  3. Step 3: p-bromoacetanilide to p-bromoaniline: H₃O⁺, heat.
Why these reagents

Reagent and reason, step by step

  • Step 1: Aniline to acetanilide: CH₃COCl, pyridine Acetylation protects the NH₂ group and lowers its activating power; the base takes up the HCl.
  • Step 2: Acetanilide to p-bromoacetanilide: Br₂, CH₃COOH The acetyl group tames the NH₂ so only one bromine enters, mainly para.
  • Step 3: p-Bromoacetanilide to p-bromoaniline: H₃O⁺, heat Hydrolysis removes the protecting acetyl group.
Questions

Aniline to p-bromoaniline: quick answers

How many steps does it take to convert aniline to p-bromoaniline?

3 steps: Aniline, then acetanilide, then p-bromoacetanilide, then p-bromoaniline.

Which named reaction is used to convert aniline to p-bromoaniline?

None of the steps has a name. They are substitution and substitution and hydrolysis, so write the reagent and the condition for each step.

What is the reagent for step 1 of aniline to p-bromoaniline?

Aniline to acetanilide: CH₃COCl, pyridine. Acetylation protects the NH₂ group and lowers its activating power; the base takes up the HCl.

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