Q4(c)(i). Two dichlorides with NaN₃: neighbouring sulfur
Compounds 1 and 2 on reaction with NaN₃ yield the same product, but compound 1 reacts at room temperature while compound 2 reacts at 200 °C. Identify the product formed and explain the reasons for the different reactivities of compounds 1 and 2. [structures of the two bicyclic sulfur-containing dichlorides 1 and 2 given in the paper]
Model answer
The free solution for 2025 answers questions 1, 3, 5, 6 and 8, the ones picked in its time plan. Question 4 is answered in full in the Chemistry Paper II, 2021 to 2025 book, with every part of every paper.
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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
Coversneighbouring group participationanchimeric assistanceepisulfonium ionazide substitutionthiabicyclononane
All parts of Question 4
- 4(a)(i) Molecular weight of poly(p-hydroxybenzoic acid)7 marks
- 4(a)(ii) Structure of the polymer3 marks
- 4(a)(iii) Precursor of natural rubber5 marks
- 4(b)(i) Nylon 6 and nylon 6,6 compared5 marks
- 4(b)(ii) Preparing syndiotactic polystyrene5 marks
- 4(b)(iii) Salient features of the α-helix5 marks
- 4(c)(i) Two dichlorides with NaN₃: neighbouring sulfur10 marks
- 4(c)(ii) Kinetic and thermodynamic enolates trapped with D₂O10 marks