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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 · 2023 · Paper II

Q5(d). Woodward–Fieser calculation and a name error

Question

Calculate λmax for A, printed as 2-methoxypent-3-en-2-one, and B, 3-methoxy-2-methylbut-2-enal, using Woodward–Fieser rules.

Answer in brief

B gives about 259 nm. A is not a valid neutral ketone name as printed: its carbonyl C2 cannot also carry methoxy, so a unique value cannot be assigned.

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Topic notes: UV spectroscopy and Woodward–Fieser rules, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversWoodward–Fieser rulesλmax calculationα,β-unsaturated carbonylenoneUV spectroscopy

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