Question

why is tertiary carbon said to be more stable than primary or secondary ?

Answer 1

Dear student!

The alkyl groups are electron donating group and so they causes +I (Inductive ) effect due to which , the charge is spreaded over the system rather than being at one center.

Now, in primary carbocation, there will be only one electron donating alkyl group, similarly in secondary carbocation there will be two alkyl groups and in tertiary carbocation there will be three alkyl groups.

Hence, due to more substituent alkyl groups, the tertiary carbocation gets maximum +I effect , which causes higher stability in the tertiary carbocations.