Indian Forest Service (Mains), Chemistry optional · 2023 · Paper II
Q6(b). Photochemical alpha cleavage
Question
Predict and explain the products from (i) Ph₂CHCOCHPh₂ under irradiation and (ii) cyclohexanone irradiated in an alcohol ROH.
Answer in brief
(i) Tetraphenylethane plus CO through radical cleavage/decarbonylation. (ii) Alkyl hexanoate through ketene trapping by ROH.
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CoversNorrish type Ialpha cleavagedecarbonylationketene trappingtetraphenylethane
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