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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

Q8(b). Aromatic proton coupling constants

Question

Do ortho, meta and para protons in a monosubstituted benzene couple? Give approximate coupling constants.

Answer in brief

Yes, when magnetically distinguishable: ortho coupling is about 6–9 Hz, meta 1–3 Hz and para commonly 0–1 Hz.

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Topic notes: ¹H and ¹³C NMR: chemical shift, spin–spin coupling and coupling constants, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coverscoupling constantsortho meta para coupling1H NMRaromatic protonsspin–spin splitting

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