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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 · 2021 · Mains Paper III

Q7(b). Maleic anhydride with anthracene, furan and pyrrole

Question

Predict the products I, II and III in the following reactions with maleic anhydride. Propose mechanisms. [anthracene (80 °C) → I, furan (35 °C) → II and pyrrole → III; scheme given in the paper]

Answer in brief

I: Diels–Alder adduct across C-9 and C-10 of anthracene. II: furan adduct, isolated as the exo isomer. III: no cycloadduct; pyrrole is substituted at C-2 to give 2-(1H-pyrrol-2-yl)succinic anhydride.

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Topic notes: pericyclic reactions, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversDiels–Alder reactionmaleic anhydrideendo ruleexo adductretro-Diels–Alderpyrrole

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