The reaction of deactivated arenes with tribromoisocyanuric acid (TBCA) in 98% H2SO4 produced bromoarenes in good yields. The acidity of the medium controls the strength of the brominating agent and the amount of polybrominated products. DFT calculations at B3LYP/6- 311++ G∗∗ level showed that the protonated TBCA (a superelectrophilic species) can easily transfer Br+ to deactivated arenes, in order to decrease internal charge–charge ...