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🧪 Chemistry  ·  Haloalkanes & Haloarenes  ·  NEET & JEE

Predict the product when (S)-2-bromobutane undergoes SN2 reaction with NaOH:

Answer: (R)-2-butanol due to inversion of configuration.

  • A (R)-2-butanol due to inversion of configuration
  • B (S)-2-butanol with retention of configuration at the stereocentre
  • C A fully racemic mixture of (R)- and (S)-2-butanol
  • D A mixture of butene isomers formed via E2 elimination instead

Correct answer: A. (R)-2-butanol due to inversion of configuration

Explanation: SN2 proceeds with inversion (Walden inversion) at the chiral centre. (S)-2-bromobutane → (R)-2-butanol. The configuration inverts.

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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