UPSC Civil Services (Mains)
Chemistry optional
- 2 papers
- 250 marks each
- 3 h per paper
- 5 of 8 questions, Q1 and Q5 compulsory
Paper II covers organic chemistry and spectroscopy.
All topics
Paper II, organic chemistry and spectroscopy
Synthetic uses of reagents: every question, 2021 to 2025
21 parts worth 200 marks have been set on this unit in UPSC CSE Chemistry Paper II from 2021 to 2025. Each one opens on its own page with the question, the answer in brief and the key points.
Syllabus
OsO₄, HIO₄, CrO₃, Pb(OAc)₄, SeO₂, NBS, B₂H₆, Na-liquid NH₃, LiAlH₄, NaBH₄, n-BuLi, MCPBA.
Notes: Reagents for oxidation, reduction and hydroboration (full notes) · short notes
2025
- Q5(b) Starting material A and the intermediates10 marks Answered
- Q6(a)(i) Products and intermediates of two reductions10 marks Answered
- Q6(a)(ii) Role of NMO in catalytic dihydroxylation5 marks Answered
2024
- Q5(b) P, Q and R from an enyne10 marks Answered
- Q6(c) A, B, C and D; mechanism of the NaBH₄ step20 marks Answered
- Q7(b) X, Y and Z from an N-Boc piperidine aldehyde15 marks Question only
2023
- Q5(d) LiAlH₄ reduction of camphor: OH cis to the bridge10 marks Answered
- Q6(b)(i) Products A, B and C10 marks Question only
- Q7(c)(i) Structures of (A), (B), (C), (D) and (E)10 marks Question only
- Q7(c)(ii) Osmate ester from cyclohexene; oxidation state and geometry of osmium5 marks Question only
- Q7(c)(iii) D-Mannitol: cyclohexylidene ketal, then HIO₄5 marks Question only
2022
- Q5(c)(i) 1-Ethynylcyclopentanol from acetylene5 marks Answered
- Q5(c)(ii) Products W, X, Y and Z from toluene5 marks Answered
- Q6(c)(i) OsO₄, then HIO₄, on an alkenyl cyclopropane lactone10 marks Answered
- Q6(c)(ii) (S)-3-Phenylbutan-2-one with m-CPBA10 marks Answered
- Q7(b)(i) Butanoyl chloride with 2 NaBH₄, then H₃O⁺10 marks Question only
- Q7(b)(ii) But-2-yne with sodium in liquid ammonia5 marks Question only
2021
- Q5(c) Acetophenone with SeO₂; benzoic acid with Na in liquid NH₃10 marks Answered
- Q7(b) LiAlH₄ and NaBH₄: solvents, reactivity and choice of reagent15 marks Question only
- Q8(a)(i) Products X and Y in four reagent problems15 marks Answered
- Q8(a)(ii) 2-Methylbut-1-ene with diborane5 marks Answered
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UPSC Civil Services (Main) Chemistry Paper II: Model Answers 2021 to 2025
- All eight questions of each paper, with the question printed above its answer
- Mechanisms drawn out and labelled on the scheme
- Topic-wise weightage and a topic-wise index