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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 · 2023 · Paper II

Q8(c)(i). Keto and enol percentages of acetylacetone from integration

Question

In the ¹H NMR spectrum of acetylacetone the height of the integration curve at the methylene (–CH₂) signal was found to be 10 mm and that of the methine (=CH) signal was 22 mm. Calculate the percentage of keto and enol form in the sample.

Answer in brief

Enol 81.5 %, keto 18.5 %; K = [enol]/[keto] = 4.4.

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Coversketo–enol tautomerismacetylacetoneNMR integrationenol contentintramolecular hydrogen bond

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