Question

Which carbene is more stable for ${\mathrm{CCl}}_2$?

• A. Singlet carbenes
• B. Triplet carbenes
• C. Both (A) and (B)
• D. None Of These

Answer 1

The correct option is A

Singlet carbenes

Explanation for correct option

(A) Singlet carbenes

Carbene

• A carbene is a kind of carbon cation that lacks a formal charge, and the other valence electron is in an orthogonal nonbonding pair to the system.
• Carbenes have both electrophilic and nucleophilic characteristics.
• Both singlet and triplet methylene are bent-shaped $s{p}^2$ hybridizations.

Singlet carbenes stability for ${\mathbf{CCl}}_{\mathbf{2}}$

• Singlet carbene is less stable than triplet carbene.
• However, singlet carbene is more stable than triplet carbene in the case of ${\mathrm{CCl}}_2$.
• No corresponding stabilization is possible for triplet carbine due to the unavailability of vacant orbital at carbon.
• As a result, when the singlet carbene has a substituent containing lone pairs, it is more stable than the triplet carbene.

Explanation for incorrect options

• Singlet carbenes is more stable for ${\mathrm{CCl}}_2$.
• Hence all the other options (B), (C) and (D) are incorrect.

Therefore, the correct option is (A) Singlet carbenes.