Bromine

Abstract

AbstractDiatomic bromine, Br2[7726‐95‐6], is the only nonmetallic element that is a liquid at standard conditions. Bromine is widely distributed in nature but in relatively small amounts, mainly as soluble bromide salts. It occurs in the form of bromide in seawater and in natural brine deposits, always together with chloride. Its concentration ranges from 65 mg/L in seawater up to 6.5 g/L in the Dead Sea and was discovered in 1826. Historically it has been important as an agent for removal of lead from combustion chambers. Nowadays, an important use of bromine compounds is in the production of flame retardants and drilling fluids, and as a component in intermediates for pharmaceutical, biocide and photographic industry, dyes, disinfectants, water treatment, and so on. Bromine is a heavy liquid, hardly soluble in water. It tends to acquire an electron to form either a negative ion, Br−, or a single covalent bond, Br. Nonmetal bromides are generally hydrolyzed to a hydrogen halide and to an oxy‐acid containing the other element. Bromine combines directly with hydrogen at elevated temperatures, when this is the basis for the commercial production of hydrogen bromide. Bromine reacts with essentially all metals, except tantalum and niobium, and also with some metal oxides. The addition of bromine to unsaturated carbon compounds occurs readily. In alkaline solution, bromine reacts rapidly to produce hypobromite. In all current methods of bromine production, chlorine, which has a higher reduction potential than bromine, is used to oxidize bromide to bromine. The price of bromine is ∼ 1.3 $/kg. The annual worldwide production is > 500,000 ton and growing slowly, with the United States and Israel as the leading manufacturers. Bromine is highly toxic and corrosive, and utmost care should be taken when handling it.