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JEE Main levelSingle correct optionDifficulty 2 of 3o1177

Which of the following esters is hydrolysed fastest by aqueous NaOH at the same temperature?

  1. Atert-butyl acetate
  2. B (4-nitrophenyl acetate)
  3. Cethyl acetate
  4. Dphenyl acetate

Answer: B

Rate depends on the leaving group (and steric access). The 4-nitrophenoxide ion (conjugate acid pKa about 7) is the weakest base and best leaving group; phenoxide (pKa about 10) is next; alkoxides (pKa 16-18) are poorest, and the tert-butyl ester is also hindered. So 4-nitrophenyl acetate is fastest.
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