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  4. Which of the following reactants on reaction with conc. NaOH followed by acidification gives the following lactone as the only product?

Q. Which of the following reactants on reaction with conc. followed by acidification gives the following lactone as the only product? Chemistry Question Image

 2014  194 JEE AdvancedJEE Advanced 2006 Report Error

Solution:

Lactones are formed when a carboxylic acid with a hydroxyl group on the adjoining carbon, undergoes intramolecular esterification.
From the given compounds,
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first undergoes intramolecular Cannizzaro's reaction to yield carboxylic compound with hydroxyl group, which on intramolecular esterification in acidic medium leads to the single product, lactone. The following is the sequence of reactions:
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