Question

How it is possible to rank radical stability?

Answer 1

The stability of radicals on the carbon atom increase with the increase of its degree (`1^(st), 2^(nd) and 3^(rd)`).

Explanation:

The stability of radicals on the carbon atom increase with the increase of its degree (`1^(st), 2^(nd) and 3^(rd)`).

For example, `R_3C*` is more stable than `R_2HC*` which is more stable than `RH_2C*`.

Alkyl groups are consider electron donating groups through inductive effect , and this will increase the stability of the radical in a similar way the stabilizes a carbocation.

Image source: Organic Chemistry-Janice Gorzynski Smith 3rd Ed .