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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 · 2021 · Paper II

Q2(c)(ii). Cyclohexanone enolate with methyl iodide and with trimethylsilyl chloride

Question

Cyclohexanone is treated with NaH in THF to give [P]; P with CH₃I gives Q and with (CH₃)₃SiCl gives R. Write down the products in the above reactions.

Answer in brief

P = sodium enolate of cyclohexanone; Q = 2-methylcyclohexanone (C-alkylation); R = 1-(trimethylsilyloxy)cyclohexene (O-silylation, a silyl enol ether).

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Topic notes: reactive intermediates (carbocations, carbanions, radicals, carbenes, nitrenes, benzyne), with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversenolate alkylationambident nucleophilesilyl enol etherHSABC- vs O-alkylation

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