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🧪 Chemistry  ·  Haloalkanes & Haloarenes  ·  NEET & JEE

Dehydrohalogenation of an alkyl halide with KOH/alcohol gives:

Answer: Alkene.

  • A Alcohol
  • B Alkane
  • C Carboxylic acid
  • D Alkene

Correct answer: D. Alkene

Explanation: Treatment with strong base (KOH in alcohol) causes elimination of HX from a haloalkane to give an alkene.

SN2: one stepNu-CX-backside attackNuC+ 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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