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UPSC Civil Services (Mains)

Chemistry optional

  • 2 papers
  • 250 marks each
  • 3 h per paper
  • 5 of 8 questions, Q1 and Q5 compulsory

Paper II covers organic chemistry and spectroscopy.

UPSC Civil Services (Mains), Chemistry optional · 2022 · Paper II

Q4(c). Phenol to coumarin

Question

By using appropriate reagents and conditions, how will you convert phenol into coumarin? Give suitable mechanism for this transformation.

Answer in brief

Phenol → salicylaldehyde (Reimer–Tiemann: CHCl₃, aq. NaOH, 65 °C, then H₃O⁺) → coumarin (Perkin: acetic anhydride, sodium acetate, 180 °C; the cis-o-hydroxycinnamic acid lactonises).

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Topic notes: carbonyl additions and condensations, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoverscoumarinReimer–Tiemann reactionPerkin reactionsalicylaldehydedichlorocarbenePechmann condensation

All parts of Question 4