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Indian Forest Service (Mains)

Chemistry optional

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

Paper II covers organic chemistry and spectroscopy.

Indian Forest Service (Mains), Chemistry optional · 2022 · Paper II

Q5(h). Labelled allylic bromination

Question

Explain the three labelled allylic bromides obtained from ¹⁴C-labelled cyclohexene with NBS/light. [structure of labelled cyclohexene given in the paper]

Answer in brief

Abstraction at either allylic site and trapping of resonance-delocalized allyl radicals account for the three distinct isotope positions.

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Topic notes: addition to alkenes and alkynes (Markovnikov, stereochemistry, dienes), with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversNBS allylic brominationallyl radical resonance14C labellingWohl–Ziegler reactioncyclohexene

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