UPSC Civil Services (Mains), Chemistry optional · 2021 · Paper II
Q5(d). Ease of Norrish type II hydrogen abstraction in two groups of ketones
Question
Arrange the compounds in each of the two groups (i) and (ii), each of three ketones I, II and III, for ease of Norrish type-II H-abstraction in decreasing order, giving plausible explanations. [structures given in the paper]
Answer in brief
(i) III > II > I. (ii) III > II > I.
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CoversNorrish type IIγ-hydrogen abstraction1,4-biradicaln,π* excited statebutyrophenone
All parts of Question 5
- 5(a) Five ¹H NMR signals of pentane-2,4-dione10 marks
- 5(b)(i) Three para-substituted styrenes in anionic polymerisation5 marks
- 5(b)(ii) Structures and configurations of natural and synthetic rubber5 marks
- 5(c) Acetophenone with SeO₂; benzoic acid with Na in liquid NH₃10 marks
- 5(d) Ease of Norrish type II hydrogen abstraction in two groups of ketones10 marks
- 5(e) McLafferty rearrangement in pentan-2-one; base peak of pentan-3-one10 marks