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
Substitution reactions: every question, 2021 to 2025
18 parts worth 140 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
SN1, SN2 and SNi mechanisms; neighbouring group participation; electrophilic and nucleophilic reactions of aromatic compounds including heterocyclic compounds: pyrrole, furan, thiophene and indole.
Notes: Aromatic substitution: electrophilic, nucleophilic and heterocycles (full notes) · short notes
Notes: Aliphatic nucleophilic substitution: SN1, SN2, SNi and neighbouring group participation (full notes) · short notes
2025
- Q4(c)(i) Two dichlorides with NaN₃: neighbouring sulfur10 marks Question only
2024
- Q1(c) (S)-2-Butanol to (S)-2-butyl chloride10 marks Answered
- Q3(c)(ii) Indole at C-3; inertness of chlorobenzene10 marks Answered
- Q4(a)(i) Furan with acetic anhydride and BF₃10 marks Question only
- Q4(a)(ii) Major products and mechanism type5 marks Question only
- Q4(b)(ii) Energy profile: benzene to chlorobenzene5 marks Question only
2023
- Q1(c) Methyl iodide with sodium azide: DMF against methanol10 marks Answered
- Q2(b)(i) Hydrolysis of bis(2-chloroethyl) sulfide and of 1,5-dichloropentane5 marks Answered
- Q2(b)(ii) Both glycosyl bromides give the β-glycoside5 marks Answered
- Q2(c)(i) Acetolysis of 2-(cyclopent-3-enyl)ethyl tosylate10 marks Answered
- Q2(c)(ii) Indole: electrophilic substitution at C-3, not C-25 marks Answered
2022
- Q1(b) (4-Nitrophenyl)oxirane with methoxide in methanol10 marks Answered
- Q2(b)(i) 2,2-Dimethyltetrahydrofuran with one equivalent of HI5 marks Question only
- Q3(b)(ii) p-Bromonitrobenzene to m-bromobenzoic acid5 marks Question only
- Q3(c)(ii) SN2 reactivity of four tertiary bromides10 marks Question only
- Q4(b)(ii) p-Nitrotoluene to m-nitrotoluene5 marks Answered
2021
- Q2(c)(i) 1-Phenylethanol with SOCl₂ and pyridine10 marks Answered
- Q3(c)(ii) 3-Iodo-2,2-dimethylbutane with silver nitrate in hot ethanol10 marks Answered
Printed copy and Kindle
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