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JEE MainChemistryAldehydes and Ketones

Which of the following structural isomers of C ₄ H ₈ O gives a positive 2,4-DNP test and is the most reactive towards nucleophilic addition reactions?

Options

  1. AButanal
  2. B2-Methylpropanal
  3. CButan-2-one
  4. DEthoxyethene

Correct answer

A. Butanal

Step-by-step solution

Compounds with the molecular formula C ₄ H ₈ O that give a positive 2,4-DNP test are aldehydes and ketones. The acyclic carbonyl isomers are butanal, 2-methylpropanal, and butan-2-one. Ethoxyethene is an ether and does not give the 2,4-DNP test. Reactivity towards nucleophilic addition depends on steric hindrance and electronic effects (+I effect). Aldehydes are generally more reactive than ketones due to less steric hindrance and having only one alkyl group donating electron density. Thus, butanal and 2-methylprop

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