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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.

UPSC Civil Services (Mains), Chemistry optional · 2025 · Paper II

Q6(a)(ii). Role of NMO in catalytic dihydroxylation

Question

Describe the role of NMO during the dihydroxylation of an alkene using a catalytic amount of OsO₄ in the presence of N-methylmorpholine N-oxide (NMO).

Answer in brief

NMO is the stoichiometric co-oxidant: it re-oxidises Os(VI) to OsO₄, so OsO₄ is needed only in catalytic amount.

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Topic notes: reagents for oxidation, reduction and hydroboration, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversNMOOsO4Upjohn dihydroxylationsyn dihydroxylationosmate esterco-oxidant

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