UPSC Combined Geo-Scientist, Mains · 2025 · Mains Paper III
Q8(b)(ii). Ozonolysis, then intramolecular aldol condensation
Question
Predict the structures of ‘A’ and ‘B’ in the following reaction sequence and give mechanism for formation of ‘B’ from ‘A’. [alkene given in the paper: (i) O₃ (ii) H₂O/Zn → A; NaOEt, EtOH, Δ → B]
Model answer
The free solution for 2025 answers questions 1, 2, 4, 6, 7 and 9, the ones picked in its time plan. Question 8 is answered in full in the Geo-Scientist Chemistry Paper III, 2021 to 2025 book, with every part of every paper.
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UPSC Combined Geo-Scientist (Main) Chemistry Paper III: Model Answers 2021 to 2025
- All ten questions of each paper, with the question printed above its answer
- Instruments drawn as labelled diagrams, numericals worked with units
- Topic-wise weightage and a topic-wise index
Coversozonolysisintramolecular aldol condensationring sizereductive work-upcyclic enone
All parts of Question 8
- 8(a)(i) 6,6-Dimethylfulvene takes up hydride; a simple alkene does not5 marks
- 8(a)(ii) Doped and non-doped conducting polymers; polyacetylene5 marks
- 8(b)(i) Wittig alkene, then epoxide and diol5 marks
- 8(b)(ii) Ozonolysis, then intramolecular aldol condensation5 marks
- 8(c)(i) [1,5]-Hydrogen shift, then ring opening of a cyclobutene5 marks
- 8(c)(ii) Oxy-Cope rearrangement of a bicyclic vinyl carbinol5 marks