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🧪 Chemistry  ·  Haloalkanes & Haloarenes  ·  NEET & JEE

Which reagents bring about Friedel–Crafts acylation of chlorobenzene?

Answer: CH3COCl with anhydrous AlCl3.

  • A CH3COOH with conc. H2SO4
  • B CH3CHO with dilute NaOH
  • C CH3COCl with anhydrous AlCl3
  • D CH3COONa with soda lime

Correct answer: C. CH3COCl with anhydrous AlCl3

Explanation: Friedel–Crafts acylation needs an acyl halide plus a Lewis acid: anhydrous AlCl3 generates the acylium ion that attacks the ring.

SN2: one stepNu-CX-backside attack↓NuC+ X-Inversion of configuration(Walden inversion)SN1: two stepsCX-slow: leaving group exits↓+CcarbocationNu-Planar intermediate givesracemisation (both faces attacked)

SN2 proceeds in a single step with backside attack and inversion of configuration, while SN1 forms a planar carbocation intermediate first, leading to racemisation.

Concept context

Study carbon-halogen compounds: how they are made, how they react via SN1/SN2 and elimination, their stereochemistry, and their environmental impact.

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