UPSC Combined Geo-Scientist, Mains · 2026 · Mains Paper III
Q7(b). Bullvalene NMR; quasi-Favorskii rearrangement
Question
(i) The ¹H-NMR spectrum of bullvalene (X) shows a single signal at δ 4.22 ppm at 10°C. Explain the observation. (ii) Suggest a suitable reaction mechanism for the following reaction: 1-methyl-4-benzoyl-4-chloropiperidine with NaOH gives 1-methyl-4-phenylpiperidine-4-carboxylic acid.
Model answer
The free solution for 2026 answers the questions picked in its time plan. Question 7 is answered in full in the Book Edition of the 2026 solutions of Geo-Scientist Chemistry Paper III.
Coversfluxional molecules; rearrangementsBullvalene NMRquasi-Favorskii rearrangement
All parts of Question 7
- 7(a) Thermal and photochemical electrocyclisations of cyclooctatriene10 marks
- 7(b) Bullvalene NMR; quasi-Favorskii rearrangement10 marks
- 7(c) Birch reduction; Michael addition and decarboxylation10 marks