The cavity induces a stabilization of the ortho (para) species in comparison to the meta by up to ∼8 kcal/mol (6 kcal/mol) with cavity frequency ω c = 4.0 eV (2.5 eV) and cavity volume V = 0.1 nm 3 (0.1 nm 3 ). The white region indicates the turning point of the cavitymediated selectivity for each polarization. For the ortho/meta selectivity, the cavity is required to have a mode volume V are required to be (for ω c ∼2.5 eV) V ∼0.7 nm 3 in order to favor the ortho selectivity. For para to be the favored product over the meta, the cavity is required to have (for ω c ∼1.5 eV ) a mode volume ofV ∼0.25 nm 3 . For reference, the volume of a single molecule (roughly the size of benzene) is ∼0.1 nm 3 . In both panels, the open circles indicate currently accessible cavity parameters based on state-of-the-art NPoM plasmonic cavities and correspond to a cavity volume of V = 0.15 nm 3 and cavity frequency ω c = 1.8 eV. At these parameters, and in both polarizations, we predict that the cavity is already able to provide the selectivity of this bromination reaction away from the expected meta product. Thus, our theoretical predictions should be experimentally realizable with current experimental cavity designs.