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JEE MainChemistryAldehydes and Ketones

A stable -lactone, 4,4-diethyl-3-hydroxydihydrofuran-2(3H)-one, is synthesized by treating an unknown aldehyde 'P' with formaldehyde and K ₂ CO ₃ , followed by reaction with KCN and subsequent acidic hydrolysis. The IUPAC name of the starting aldehyde 'P' is:

Options

  1. A2-methylpentanal
  2. B2-ethylbutanal
  3. C3-ethylpentanal
  4. DHexanal

Correct answer

B. 2-ethylbutanal

Step-by-step solution

1. The final product is 4,4-diethyl-3-hydroxydihydrofuran-2(3H)-one. This is a -lactone formed by the intramolecular esterification of a -hydroxy acid. 2. Opening the lactone ring retrosynthetically yields the acyclic intermediate: 3-ethyl-2-hydroxy-3-(hydroxymethyl)pentanoic acid. 3. The -hydroxy acid moiety is formed from the acidic hydrolysis of a cyanohydrin. Working backwards, the cyanohydrin precursor must be 3-ethyl-2-hydroxy-3-(hydroxymethyl)pentanenitrile. 4. This cyanohydrin is formed by the nucleophilic

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