radical stability question

[queenskillers]

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if a radical Br were to add on to a methelene cyclopentane (Q82 achiever first test), why would it not attach to the cyclopentane ring itself. why would the radical attach to the methelene group instead. arent radicals stabilized by tert>sec>prim?

 

[jleefe]

if a radical Br were to add on to a methelene cyclopentane (Q82 achiever first test), why would it not attach to the cyclopentane ring itself. why would the radical attach to the methelene group instead. arent radicals stabilized by tert>sec>prim?

I noticed I got the same question wrong for the same reason.
Focus on the double bond. For alkanes, 3>2>1 radical stability applies, but radical Bromination across a double bond is anti-markovnikov.

 

[Jaylee777]

yes your right about the stability of the radicals but your not considering the mechanism. The BR radical formed from light attacks the molecule. The reason it attacks the outside carbon is because by doing so it forms the radical on the tertiary carbon and thus producing the more stable radical which then gets protonated. one electron from the double bond forms with the halide radical and the other electron jumps onto the adjacent carbon. Hope that helps