Question

The order of stability of the following carbocations:

Answer 1

Carbocation:

• Carbocation is an ion having a carbon atom bearing a positive charge having three bonds.
• Carbocation is having a planar geometry.
• In Carbocation, the carbon will have ${\mathrm{sp}}^2$ hybridization.

Stability of carbocation:

• The order of stability of the given carbocation is: $\mathrm{III}>\mathrm{I}>\mathrm{II}$
• The stability of carbocation is directly proportional to the extent of delocalization.
• The structure $\mathrm{I}$ is an aromatic compound having a planar, cyclic, conjugated system with $6\mathrm{\pi }-$electrons and it is resonance stabilized i.e, delocalization is possible. so this is a more stable carbocation.
• The structure $\mathrm{II}$ allyl carbocation is having resonance stabilized and delocalisation is possible in this structure. So, it is the second stable carbocation.
• Then the structure $\mathrm{III}$ propyl carbocation is having a methyl group so it exhibits a +I effect so, that is the least stable carbocation.

The order of stability of the given carbocation is: