Brominated organic molecules are used commercially as flame retardants, why is that? (I thinks that the three following contributors are important: 1. Br-containing molecules act as traps for free radicals, so they speed up free radical chain termination; 2. Non-combustible molecules (HBr and Br2) are produced, and they extinguish fire like carbon dioxide; 3. Bromine does not bond well with oxygen, so the energy spend on breakage of the C-Br and C-H is not compensated enough by a relatively weak H-Br bond. - GS).