Once all N-bromosuccinimide (which is denser than the solvent) has been converted to succinimide (which floats on top) the reaction has finished.
Due to the high toxicity and ozone-depleting nature of carbon tetrachloride, trifluorotoluene has been proposed as an alternative solvent suitable for the Wohl-Ziegler bromination.
[10] The generation of NBS radicals depicted in the Bloomfield mechanism has been shown to be far more difficult than imagined when it was proposed, which is why it has failed as a proper model throughout the years; however, evidence suggests that the Bloomfield mechanism is still acceptable for the oxidation of alcohols using NBS.
[10] In the Goldfinger mechanism, the purpose of the NBS is simply to maintain a very low concentration of molecular bromine, while in the Bloomfield mechanism, its purpose is the generation of the initial radical used in the reaction,[11] which again can be quite a difficult process.
[12] This is because it requires a special consideration for the behavior of the NBS radical; the only way it can possibly function as proposed in Bloomfield's mechanism is if the dissociation energy for the N-Br bond in NBS is smaller than that for Br2, and much evidence has been seen to suggest contrary behavior.