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UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper III covers analytical and organic chemistry.

UPSC Combined Geo-Scientist, Mains · 2022 · Mains Paper III

Q7(d). Phenyl acetate to A, B, C, D: Reimer–Tiemann and Wittig reactions

Question

Complete the following reaction and sketch a suitable mechanism for conversion of A → B and B → C: [phenyl acetate → (H₃O⁺) A → (CHCl₃, KOH) B → (Ph₃P⁺–CH₂⁻) C → (HBr, peroxide) D; structures given in the paper]

Answer in brief

A = phenol; B = salicylaldehyde (Reimer–Tiemann); C = 2-vinylphenol (Wittig); D = 2-(2-bromoethyl)phenol (anti-Markovnikov HBr addition).

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Topic notes: reactive intermediates (carbocations, carbanions, radicals, carbenes, nitrenes, benzyne), with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversReimer–Tiemann reactiondichlorocarbeneWittig reactionsalicylaldehydeanti-Markovnikov additionperoxide effect

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