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Organic conversion

Benzene to p-bromonitrobenzene

2 steps: substitution, then substitution

Class 12, Chapter 6 Haloalkanes and Haloarenes

  1. BenzeneC₆H₆Arene
  2. Step 1

    Br₂, anhydrous FeBr₃

    i

    Electrophilic substitution; the Lewis acid polarises Br₂.

    Br
    BromobenzeneC₆H₅BrHaloarene
  3. Step 2

    conc. HNO₃ + conc. H₂SO₄

    i

    Halogens deactivate the ring but direct ortho and para; the para isomer is the major product.

    O−N+OBr
    p-Bromonitrobenzenep-BrC₆H₄NO₂Nitro compound

Exam answer

  1. Step 1: Benzene to bromobenzene: Br₂, anhydrous FeBr₃.
  2. Step 2: Bromobenzene to p-bromonitrobenzene: conc. HNO₃ + conc. H₂SO₄.
Why these reagents

Reagent and reason, step by step

  • Step 1: Benzene to bromobenzene: Br₂, anhydrous FeBr₃ Electrophilic substitution; the Lewis acid polarises Br₂.
  • Step 2: Bromobenzene to p-bromonitrobenzene: conc. HNO₃ + conc. H₂SO₄ Halogens deactivate the ring but direct ortho and para; the para isomer is the major product.
Questions

Benzene to p-bromonitrobenzene: quick answers

How many steps does it take to convert benzene to p-bromonitrobenzene?

2 steps: Benzene, then bromobenzene, then p-bromonitrobenzene.

Which named reaction is used to convert benzene to p-bromonitrobenzene?

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

What is the reagent for step 1 of benzene to p-bromonitrobenzene?

Benzene to bromobenzene: Br₂, anhydrous FeBr₃. Electrophilic substitution; the Lewis acid polarises Br₂.

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