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Chemistry Question on Aldehydes, Ketones and Carboxylic Acids

The relative reactivities of acyl compounds towards nucleophilic substitution are in the order of

A

acyl chloride > acid anhydride > ester > amide

B

ester > acyl chloride > amide > acid anhydride

C

acid anhydride > amide > ester > acyl chloride

D

acyl chloride > ester > acid anhydride > amide

Answer

acyl chloride > acid anhydride > ester > amide

Explanation

Solution

In acyl compounds (i.e. acyl chloride, acid
anhydride, ester and amide) RCO- group is same,
thus reactivity depends upon the nature of group Z
(i.e. Cl, RCOO−,R′O−,NH2−RCOO^-, R'O^-, NH_2^-, etc.)
If group Z is a weak base, then it is a strong leaving
agent and its reactivity towards nucleophilic
substitution is high.
The order of basic nature of Z groups is
\hspace10mm Cl^- < RCOO^- < R' O^- > NH_2^-
Thus, order of reactivity is
Acyl chloride     Acid anhydride   Ester    RCOCI     >     (RCO)2O     >RCOOR′        Amide>RCONH2_{Acyl \, chloride \, \, \, \, \, Acid \, anhydride \, \, \, Ester}^{ \, \, \, \, RCOCI \, \, \, \, \, > \, \, \, \, \, (RCO)_2 O \, \, \, \, \, > RCOOR'} { \, \, \, \, \, \, \, \, Amide }^{>RCONH_2}