Question

Which of the most reactive acid derivative?

• A. R-COCl
• B. $(RCO{)}_{2}O$
• C. RCOOR
• D. $RCON{H}_2$

Answer 1

The correct option is A R-COCl

Carboxylic acid derivatives tend to react via nucleophilic acyl substitution where the group on the acyl unit, $R-C=O$ undergoes substitution. The reactivity depends on the the ability of the substituent to function as a leaving group. $C{l}^{-}$ as the electron withdrawing group creates more positive charge on $CO$ and is the best leaving group therefore $RCOCl$ is the most reactive acid derivative.