Electrophilic Aromatic Substitution of phenols What happens if 2,4,6-tribromophenol is forced to undergo further bromination?

In phenol, the benzene ring is activated towards electrophilic substitution. Therefore, phenol on bromination gives 2,4,6-tribromophenol. If now, 2, 4, 6-tribromophenol is forced to undergo bromination, the group attached to the benzene nucleus makes phenol not suitable to undergo Friedel–Crafts reaction due to adduct formation with Lewis acid.
Way overthinking this.  Kohn reports that 2,4,6-tribromophenol can be further brominated to pentabromophenol by adding more bromine and an iron catalyst.  Subsequently the pentabromophenol is oxidized by fuming nitric acid to give a fully brominated quinone.