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 years
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Paper II, organic chemistry and spectroscopy
Question paper, 2022
UPSC Civil Services (Mains), Chemistry optional. 15 pages, as issued by UPSC.
Every question of 2022, one page each44 parts in 8 questions, with the question as text and the key points of its answer
Question 1 50 marks
- 1(a)Ionisation of 3,4-dichloro-1,2,3,4-tetramethylcyclobutene in SbF₅–SO₂10 marks
- 1(b)(4-Nitrophenyl)oxirane with methoxide in methanol10 marks
- 1(c)The reaction that is not a condensation, and its mechanism10 marks
- 1(d)Acid-catalysed rearrangement of two phenyl-substituted 1,2-diols10 marks
- 1(e)Heating cyclopentadiene10 marks
Question 2 50 marks
- 2(a)Products X and Y in three reactions15 marks
- 2(b)(i)2,2-Dimethyltetrahydrofuran with one equivalent of HI5 marks
- 2(b)(ii)1,2-Dihydronaphthalene with NBS, then sodium ethoxide5 marks
- 2(b)(iii)Alkenes from 2-chloro-2,3-dimethylpentane with sodium ethoxide5 marks
- 2(c)(i)Matching three heterocycle syntheses; mechanism of the indole synthesis10 marks
- 2(c)(ii)L-Dopa from L-tyrosine10 marks
Question 3 50 marks
- 3(a)Acetal and ortho-ester Claisen rearrangements of an allylic alcohol15 marks
- 3(b)(i)Ergosterol, precalciferol and the need for sunlight10 marks
- 3(b)(ii)p-Bromonitrobenzene to m-bromobenzoic acid5 marks
- 3(c)(i)Cl₂CH–CF₃ with ethoxide: product and energy profile10 marks
- 3(c)(ii)SN2 reactivity of four tertiary bromides10 marks
Question 4 50 marks
Question 5 50 marks
- 5(a)Nucleosides, nucleotides and the primary structure of DNA and RNA10 marks
- 5(b)Photolysis of 2-methylcyclohexanone in solution10 marks
- 5(c)(i)1-Ethynylcyclopentanol from acetylene5 marks
- 5(c)(ii)Products W, X, Y and Z from toluene5 marks
- 5(d)N–H stretching of amines in IR; alcohols in PMR10 marks
- 5(e)Matching three sets of IR and NMR data with five structures10 marks
Question 6 50 marks
- 6(a)(i)Photolysis of a mixture of valerophenone and 5,5-dideuteriohexan-2-one5 marks
- 6(a)(ii)Photolysis of 4,5-dimethylheptan-2-one10 marks
- 6(b)(i)Polypropylene by Ziegler–Natta catalysis10 marks
- 6(b)(ii)Perlon (nylon-6) from ε-caprolactam5 marks
- 6(c)(i)OsO₄, then HIO₄, on an alkenyl cyclopropane lactone10 marks
- 6(c)(ii)(S)-3-Phenylbutan-2-one with m-CPBA10 marks
Question 7 50 marks
- 7(a)Secondary structures of proteins compared with tertiary structure15 marks
- 7(b)(i)Butanoyl chloride with 2 NaBH₄, then H₃O⁺10 marks
- 7(b)(ii)But-2-yne with sodium in liquid ammonia5 marks
- 7(c)(i)Compound A (M = 102) and its cleavage products B and C10 marks
- 7(c)(ii)Three isomeric carbonyl compounds C₅H₁₀O10 marks
Question 8 50 marks
- 8(a)(i)Carbonyl stretching frequency of two acetylcyclohexenes5 marks
- 8(a)(ii)Dehydration of 1,2-dimethylcyclohexanol; telling the alkenes apart by IR10 marks
- 8(b)(i)λmax of two polyenes by Woodward–Fieser rules10 marks
- 8(b)(ii)λmax of 1,3-butadiene and 1,3,5-hexatriene5 marks
- 8(c)(i)McLafferty rearrangement; fragmentation of butyl butyrate10 marks
- 8(c)(ii)C₂H₂BrCl with J = 16 Hz; two dienones from UV data10 marks