Chemistry Carboxylic Acids PMDC 2020
PMDC Verified Question 57 of 94
The exact reactivity order for carboxylic acid derivatives is:
A
Anhydride > Acyl chloride > Ester
B
Ester > Anhydride > Acyl chloride
C
Amide > Acyl chloride > Ester
D
Acyl chloride > Anhydride > Ester
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Acyl chloride > Anhydride > Ester
Concept:

The reactivity of acyl derivatives is governed by how well the substituent can act as a leaving group. Weaker bases constitute better leaving groups.

Solution:

  • Acyl chlorides: \( \text{Cl}^- \) is a very weak base (conjugate of strong \( \text{HCl} \)), making it the best leaving group. (Most reactive).


  • Acid anhydrides: The carboxylate ion (\( \text{RCOO}^- \)) is a moderate leaving group.


  • Esters: The alkoxide ion (\( \text{RO}^- \)) is a strong base and poor leaving group.


  • Amides: The amide ion (\( \text{NH}_2^- \)) is a very strong base and terrible leaving group. (Least reactive).


Why other options are incorrect:

Only Option D perfectly maps the sequence from weakest base leaving group to stronger base leaving group.

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