Question

Order of hydrolysis for the following: (I) $RCOCl$ (II) $RCOOR$ (III) $RCON{H}_2$ (IV) ${(RCO)}_{2}O$

• A. I > IV> II > III
• B. I > II > III > IV
• C. I > III > II > IV
• D. IV > III > II > I

Answer 1

Answer: (A)

In acid derivatives acid chlorides is most reactive, it is vigorously hydrolysed by water. $C{H}_{3}COCl+H_{2}O\to C{H}_{3}COOH+HCl$ Acid anhydride is less reactive than acid chlorides. It is hydrolysed slowly by water. ${(C{H}_{3}CO)}_{2}O+H_{2}O\stackrel{slow}{\to }2C{H}_{3}COOH$ The hydrolysis of ethyl acetate in boiling water is slow but in the presence of acid or alkali the reaction is fast. $C{H}_{3}CO-O{C}_2{H}_5+H_{2}OC{H}_{3}COOH$ $+C_2{H}_{5}OH$ Amides are hydrolysed by water very slowly. $R-\stackrel{\begin{array}{c}O\\ ||\end{array}}{C}-N{H}_2+H_{2}O\stackrel{H^{+}}{\to }R-COOH+N{H}_3$ Thus, the correct order of hydrolysis is $RCOCl>{(RCO)}_{2}O>RCOOR>RCON{H}_2$