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🧪 Chemistry  ·  Haloalkanes & Haloarenes  ·  NEET & JEE

The Reimer-Tiemann reaction is not applicable to haloalkanes because:

Answer: The reaction requires a phenolic substrate; haloalkanes lack the activating -OH group on an aromatic ring.

  • A Haloalkanes generally cannot be mixed safely with chloroform and aqueous base together according to most researchers
  • B The reaction requires a phenolic substrate; haloalkanes lack the activating -OH group on an aromatic ring
  • C Haloalkanes are far too chemically reactive to survive the reaction conditions in the majority of cases studied
  • D Haloalkanes fail to dissolve in the aqueous sodium hydroxide solution used as widely reported in standard practice

Correct answer: B. The reaction requires a phenolic substrate; haloalkanes lack the activating -OH group on an aromatic ring

Explanation: The Reimer-Tiemann reaction introduces a -CHO group ortho to the -OH in phenols using CHCl₃/NaOH via a dichlorocarbene intermediate. Haloalkanes do not have the aromatic ring with a phenolic -OH group needed to activate and direct the reaction.

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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