Indian Forest Service (Mains), Chemistry optional · 2023 · Paper II
Q6(e). Intensity of alkene and ketone UV absorption
Question
Which gives higher-intensity UV–visible absorption: trans-but-2-ene or acetone? Explain.
Answer in brief
The alkene allowed π→π* band is much stronger than the familiar weak acetone n→π* band.
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Coversπ→π* transitionn→π* transitionmolar absorptivityUV spectroscopyforbidden transition
All parts of Question 6
- 6(a) Selective reduction and alpha oxidation10 marks
- 6(b) Photochemical alpha cleavage10 marks
- 6(c) Two C3H6O carbonyl compounds5 marks
- 6(d) Meaning of a coupling constant5 marks
- 6(e) Intensity of alkene and ketone UV absorption5 marks
- 6(f) Isotopic substitution in rotational spectra5 marks