Is N-bromosuccinamide more selective than N-Chlorosuccinamide or TCCA when conducting radical halogenations?

Radical bromination in UV light for instance, is known to strongly favor bromination at the most substituted positions compared to chlorination if elemental bromine and chlorine are the halogenating reagents being compared. Does the same hold for NBS vs NCS or similar chemicals?




The reaction tends **always** to generate the more stable intermediate (carbocation, carbanion or radical).


With reagents like NBS or NCS the difference is that you generate *in situ* the halogen radical you need, and is much more selective. Usually, these types of reagents are used to create an *allylic halide* or *benzylic* ones.


 1