Why Do Radicals React Differently with Br?

[Nick tringali]

Alright so in organic chemistry we learn that for radicals and carbocations, the tertiary radical is the most stable (of primary and secondary). Okay, so why when we are predicting the major product of the reaction, let's take Br for example, the Br is going to attach to the tertiary radical. If tertiary is the "more stable" one, shouldn't Br seek out the less stable radical like a primary radical. fluorine is very unstable and fluorine will react with everything. A Nobel gas is very stable and will react with nothing. When looking at another slide on my powerpoint, it says that secondary hydrogens are way more reactive than primary hydrogens, this makes sense because when I am trying to find the major products of a reaction, I will place my Br where the secondary hydrogen was. The semantics of this makes no sense to me. Why is a Br going to attach on a "more stable" tertiary radical than a less stable primary radical. I hope I articulated this question well enough. Please try to explain this in layman's terms.

 

[Nick tringali]

In otherwords why is Br going to react with the most stable radical. But, Br is going to also take the place of the most reactive tertiary hydrogen. How does that make any sense.

 

[Borek]

Br will most often react with the carbocation/radical that is present in the largest amount - and the most stable one dominates the mixture.