Question

The CORRECT statement(s) about carbene is(are)

• A. Carbene is a neutral species
• B. Carbene is an intermediate in the Curtius rearrangement
• C. Carbene can insert into both \( \sigma \) and \( \pi \)-bonds
• D. Carbene is generated from amines on reaction with nitrous acid

Hint:

Carbenes are neutral species that are highly reactive intermediates, capable of inserting into both \( \sigma \)- and \( \pi \)-bonds.

Answer 1

The Correct Option is A, C

Step 1: Understanding carbenes. 
Carbenes are highly reactive species with a neutral carbon atom bonded to two substituents and having two electrons in an empty \( p \)-orbital. They are generally intermediates in reactions and can be formed by the reaction of amines with nitrous acid. They can insert into both \( \sigma \)- and \( \pi \)-bonds, forming new bonds. 
 

Step 2: Analyzing the options. 
(A) Carbene is a neutral species: Correct — Carbenes are neutral species with a carbon atom in a divalent state. 
(B) Carbene is an intermediate in the Curtius rearrangement: Incorrect — the key intermediates in the Curtius rearrangement are an acyl azide, a nitrene. 
(C) Carbene can insert into both \( \sigma \) and \( \pi \)-bonds: Correct — Carbenes are capable of inserting into both \( \sigma \) and \( \pi \)-bonds to form new compounds. 
(D) Carbene is generated from amines on reaction with nitrous acid: Incorrect — While carbenes are generated from diazo compounds in some reactions, nitrous acid primarily forms diazonium salts, not directly carbenes from amines. 
 

Step 3: Conclusion. 
The correct answers are (A) and (C).