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?
$\begingroup$
$\endgroup$
1
-
1$\begingroup$ NBS is not the overall brominating agent. Bromine is. HBr liberated in the radical bromination catalyzes the slow release of bromin from the NBS, which is only slightly soluble in CCl4. I suppose the same applies to NCS. $\endgroup$– user55119Mar 14, 2022 at 15:46
Add a comment
|
1 Answer
$\begingroup$
$\endgroup$
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.
