Q7(c)(ii). Osmate ester from cyclohexene; oxidation state and geometry of osmium
From the reaction sequence below (cyclohexene with OsO₄ and pyridine giving (A), then (B)), answer the following: (I) Write the structures of (A) and (B). (II) Write the oxidation state of osmium in the intermediate (A) and its geometry. [scheme given in the paper]
Model answer
The free solution for 2023 answers questions 1, 2, 3, 5 and 8, the ones picked in its time plan. Question 7 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
CoversOsO₄ dihydroxylationosmate estersyn dihydroxylationoxidation state of osmiumcis-diol
All parts of Question 7
- 7(a) 2′-Deoxycytidine-3′-monophosphate; acidity; duplex stability; G≡C pairing15 marks
- 7(b)(i) Vapour-phase photolysis of cyclopentanone10 marks
- 7(b)(ii) Direct and benzophenone-sensitised photolysis of 1,3-butadiene5 marks
- 7(c)(i) Structures of (A), (B), (C), (D) and (E)10 marks
- 7(c)(ii) Osmate ester from cyclohexene; oxidation state and geometry of osmium5 marks
- 7(c)(iii) D-Mannitol: cyclohexylidene ketal, then HIO₄5 marks