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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3hc260

The alkyne shown is converted to carbonyl compounds by (i) / and (ii) hydroboration-oxidation with followed by /. Which statements are correct?

  1. AHydration with / gives a mixture of two ketones.
  2. BHydroboration-oxidation gives an aldehyde.
  3. CThe two ketones obtained are constitutional isomers.
  4. DBoth methods give the same pair of ketones.

Answer: A, C, D

The compound shown is hex-2-yne, an unsymmetrical internal alkyne. Either route places the oxygen on either alkyne carbon, giving hexan-2-one and hexan-3-one, which are constitutional isomers. An aldehyde needs a terminal alkyne, and the internal alkyne cannot give one. So statements 1, 3 and 4 are correct.
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