Question

Curtius rearrangement is

• A. $RCO{N}_3\stackrel{\Delta }{\to }\text{Isocyanate}\stackrel{H_{2}O}{\to }RN{H}_2$
• B. $RCOOH+H{N}_3\stackrel{H_{2}S{O}_4}{\to }RN{H}_2$
• C. $RCONHOH\stackrel{{}^{-}OH}{\to }RN{H}_2$
• D. $\text{Nitrobenzene}\stackrel{H_2,Pt}{\to }\text{Aniline}$

Answer 1

The correct option is A $RCO{N}_3\stackrel{\Delta }{\to }\text{Isocyanate}\stackrel{H_{2}O}{\to }RN{H}_2$

In Curtius rearrangement, acyl halides will react with sodium azide to give primary amines.

Mechanism of Curtius rearrangement:
1. Azide ion will attack the acyl carbon and replace the $Cl$ atom to acyl azide.
2. On heating the acyl azide, $N_2$ gets eliminated and the alkyl group gets migrated to form a isocyanate intermediate.
3. Isocyanate on hydrolysis gives primary amine and $C{O}_2$.
Hence, option (a) represent Curtius rearrangement.
Option (b) represent Schmidt rearrangement
Option (c) represent Lossen rearrangement
Option (d) represent catalytic reduction of nitro group to amino group.