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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

Q8(a)(ii). 2-Methylbut-1-ene with diborane

Question

Predict the product in the reaction of 2-methyl-1-butene with diborane. Account for the regioselectivity observed in the reaction.

Answer in brief

Tris(2-methylbutyl)borane, [CH₃CH₂CH(CH₃)CH₂]₃B: boron adds to the terminal CH₂ carbon (about 99 %), hydrogen to the more substituted carbon.

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

Covershydroborationdiboraneanti-Markovnikovregioselectivitytrialkylborane

All parts of Question 8