VKC ScienceChemistry for written exams Telegram

UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper I covers inorganic chemistry.

UPSC Combined Geo-Scientist, Mains · 2025 · Mains Paper I

Q4(a). Wilkinson’s catalyst; hydrogenation cycle

Question

What is Wilkinson’s catalyst? Outline the catalytic cycle for the hydrogenation of alkene as catalysed by this catalyst.

Answer in brief

Wilkinson’s catalyst is [RhCl(PPh₃)₃], a square-planar 16-electron Rh(I) d⁸ complex that hydrogenates C=C at 25 °C and 1 atm H₂ via dissociation, oxidative addition, alkene coordination, migratory insertion and reductive elimination.

Part of VKC Basic

Read the key points and the full model answer with VKC Basic

VKC Basic (₹999 for 6 months) opens every solved answer, the notes, the handbook and the daily answer archive. Every Mains test series includes it.

See what is included Already a member? Sign in

The full model answer

As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.

The handwritten model answer pages open with the VKC plan.
Read the whole 2025 solution2025 question paper

Topic notes: organometallics: 18-electron rule, oxidative addition, fluxional molecules and Wilkinson's catalyst, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversWilkinson's catalystRhCl(PPh3)3homogeneous hydrogenationcatalytic cycleoxidative additionmigratory insertion

All parts of Question 4