UPSC Civil Services (Mains), Chemistry optional · 2025 · Paper II
Q3(a)(ii). Ketone A from isobutanol alone
Question
Describe the synthesis of ketone (A) when only isobutanol is available as the starting material. [structure of A given in the paper]
Answer in brief
A = 2,5-dimethylhexan-3-one, made by Grignard addition of isobutylmagnesium bromide to isobutyraldehyde, then oxidation.
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CoversGrignard reagentPCC oxidationisobutanolretrosynthesis2,5-dimethylhexan-3-one
All parts of Question 3
- 3(a)(i) Products of two reactions10 marks
- 3(a)(ii) Ketone A from isobutanol alone5 marks
- 3(b)(i) Cyclopropane from tert-butyl chloroacetate and ethyl acrylate10 marks
- 3(b)(ii) Structures of C and D5 marks
- 3(c)(i) Missing reagents and intermediate10 marks
- 3(c)(ii) Photolysis of the α-diazoketone in methanol10 marks