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Spectroscopy

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Question 1

Analysis of an unknown organic compound K produces the following results.

Elemental analysis by mass of compound K

  • Carbon (C): 80.60%
  • Hydrogen (H): 7.46%
  • Oxygen (O): 11.94%

Mass spectrum of compound K

  • Key peaks at m/z=134m/z = 134m/z=134 (molecular ion peak), 105 (base peak), and 77.

IR spectrum of compound K

  • Strong absorption at 1685 cm-1
  • Absorptions at 1600 cm-1 and 1450 cm-1
  • Absorptions just above and just below 3000 cm-1

Proton (1H^1\text{H}1H) NMR spectrum of compound K

  • Multiplet at δ=7.4−8.0 ppm\delta = 7.4 - 8.0\text{ ppm}δ=7.4−8.0 ppm, relative peak area = 5
  • Quartet at δ=3.0 ppm\delta = 3.0\text{ ppm}δ=3.0 ppm, relative peak area = 2
  • Triplet at δ=1.2 ppm\delta = 1.2\text{ ppm}δ=1.2 ppm, relative peak area = 3

Determine the structure of compound K, showing all your reasoning.

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Markscheme

Spectroscopy Questions

  1. A Level
  2. /Chemistry
  3. /Spectroscopy

28 exam-style questions on OCR A A Level Chemistry Spectroscopy. Each one has a worked solution and a mark scheme showing where the marks go.

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