Abstract: The near-identity of the selectivities of molecular bromine, N-bromosuccinimide (NBS), and N-bromotetramethylsuccinimide (NBTMS) obtained from competitive allylic bromination studies provides strong evidence that the operative mechanism in NBS allylic bromination is one involving Br* as the chain-carrying species. The NBS acts to provide a low steady-state concentration of Brz in a mechanism similar to that (originally suggested ...