Q6(a)(i). Photolysis of a mixture of valerophenone and 5,5-dideuteriohexan-2-one
Predict the products in the following reactions: a mixture of valerophenone and 5,5-dideuteriohexan-2-one is irradiated (hν). Propose suitable mechanism to justify your answer. [structures given in the paper]
Answer in brief
Each ketone cleaves by its own Norrish type II reaction: valerophenone gives acetophenone + propene; the labelled ketone gives CH₃COCH₂D + CH₂=CD–CH₃; no deuterium crosses over, so γ-hydrogen transfer is intramolecular.
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CoversNorrish type IIcrossover experimentdeuterium labellingγ-hydrogen abstraction1,4-biradicalvalerophenone
All parts of Question 6
- 6(a)(i) Photolysis of a mixture of valerophenone and 5,5-dideuteriohexan-2-one5 marks
- 6(a)(ii) Photolysis of 4,5-dimethylheptan-2-one10 marks
- 6(b)(i) Polypropylene by Ziegler–Natta catalysis10 marks
- 6(b)(ii) Perlon (nylon-6) from ε-caprolactam5 marks
- 6(c)(i) OsO₄, then HIO₄, on an alkenyl cyclopropane lactone10 marks
- 6(c)(ii) (S)-3-Phenylbutan-2-one with m-CPBA10 marks