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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 · 2025 · Paper II

Q5(d). Proton NMR of dry ethanol

Question

Give approximate shifts, multiplicities and integrations of pure ethanol in anhydrous CDCl₃.

Answer in brief

CH₃: about 1.2 ppm, triplet, 3H; CH₂: about 3.6 ppm, quartet of doublets if OH coupling is resolved, 2H; OH: variable, often a triplet under slow exchange, 1H.

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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 →

Covers¹H NMR of ethanolOH proton exchangespin–spin couplingD₂O exchangemultiplicity

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