Editing Bromine (section)

===Flame retardants===
[[File:Tetrabromobisphenol A.svg|thumb|left|Tetrabromobisphenol A]]

[[Brominated flame retardant]]s represent a commodity of growing importance, and make up the largest commercial use of bromine. When the brominated material burns, the flame retardant produces [[hydrobromic acid]] which interferes in the radical [[chain reaction]] of the [[oxidation]] reaction of the fire. The mechanism is that the highly reactive hydrogen radicals, oxygen radicals, and [[hydroxyl radical]]s react with hydrobromic acid to form less reactive bromine radicals (i.e., free bromine atoms). Bromine atoms may also react directly with other radicals to help terminate the free radical chain-reactions that characterise combustion.<ref>{{Cite journal|journal = Journal of Fire Sciences|volume = 14|pages = 426–442| date = 1996|doi = 10.1177/073490419601400602|title = Mechanisms for Flame Retardancy and Smoke suppression – A Review|first =Joseph|last = Green|issue = 6 |s2cid = 95145090}}</ref><ref>{{Cite journal|journal = Polymer Degradation and Stability|volume = 77|date = 2002|pages = 325–331| doi = 10.1016/S0141-3910(02)00067-8|title = Fire retardant mechanism of aliphatic bromine compounds in polystyrene and polypropylene|first = Jelle|last = Kaspersma|author2 = Doumena, Cindy|author3 = Munrob Sheilaand|author4 = Prinsa, Anne-Marie|issue = 2}}</ref>

To make brominated polymers and plastics, bromine-containing compounds can be incorporated into the polymer during [[polymerisation]]. One method is to include a relatively small amount of brominated monomer during the polymerisation process. For example, [[vinyl bromide]] can be used in the production of [[polyethylene]], [[polyvinyl chloride]] or [[polypropylene]]. Specific highly brominated molecules can also be added that participate in the polymerisation process. For example, [[tetrabromobisphenol A]] can be added to [[polyester]]s or epoxy resins, where it becomes part of the polymer. Epoxies used in [[printed circuit board]]s are normally made from such flame retardant [[resin]]s, indicated by the FR in the abbreviation of the products ([[FR-4]] and [[FR-2]]). In some cases, the bromine-containing compound may be added after polymerisation. For example, [[decabromodiphenyl ether]] can be added to the final polymers.<ref>{{Cite journal|journal = Journal of Fire Sciences|volume = 22|pages = 25–40| date = 2004|doi = 10.1177/0734904104038107|title = A Review of Current Flame Retardant Systems for Epoxy Resins|first = Edward D.|last = Weil|author2=Levchik, Sergei|s2cid = 95746728}}</ref>

A number of gaseous or highly volatile brominated [[halomethane]] compounds are non-toxic and make superior fire suppressant agents by this same mechanism, and are particularly effective in enclosed spaces such as submarines, airplanes, and spacecraft. However, they are expensive and their production and use has been greatly curtailed due to their effect as ozone-depleting agents. They are no longer used in routine fire extinguishers, but retain niche uses in aerospace and military automatic fire suppression applications. They include [[bromochloromethane]] (Halon 1011, CH{{sub|2}}BrCl), [[bromochlorodifluoromethane]] (Halon 1211, CBrClF{{sub|2}}), and [[bromotrifluoromethane]] (Halon 1301, CBrF{{sub|3}}).<ref name="UllmannF">Siegemund, Günter; Schwertfeger, Werner; Feiring, Andrew; Smart, Bruce; Behr, Fred; Vogel, Herward; McKusick, Blaine (2002) "Fluorine Compounds, Organic" Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a11_349}}</ref>