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UPSC Combined Geo-Scientist

Chemist

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

Mains Paper III covers analytical and organic chemistry.

UPSC Combined Geo-Scientist, Mains · 2016 · Mains Paper III

Q11(a). Enhanced acidity of Meldrum acid

Question

Rationalise pKₐ 7.42 for Meldrum' s acid versus 15.87 for dimethyl malonate.

Answer in brief

The cyclic ester conformation changes the relative stabilisation of the neutral molecule and its enolate, making Meldrum' s acid much more acidic.

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CoversEnhanced acidity of Meldrum acidStereoelectronic effects

All parts of Question 11