Abromideion is the negatively charged form (Br−) of the elementbromine, a member of thehalogens group on theperiodic table. Most bromides are colorless. Bromides have many practical roles, being found in anticonvulsants, flame-retardant materials, and cell stains.[3] Although uncommon, chronic toxicity from bromide can result inbromism, a syndrome with multiple neurological symptoms. Bromide toxicity can also cause a type of skin eruption, seepotassium bromide. The bromide ion has anionic radius of 196 pm.[4]
Bromide is present in typicalseawater (35 PSU) with a concentration of around 65 mg/L, which is about 0.2% of all dissolvedsalts. Seafood and deep sea plants generally have higher levels than land-derived foods.Bromargyrite—natural, crystalline silver bromide—is the most common bromide mineral known but is still very rare. In addition to silver, bromine is also in minerals combined with mercury and copper.[5]
Bromide salts ofalkali metal,alkaline earth metals, and many other metals dissolve in water (and even some alcohols and a few ethers) to give bromide ions. The classic case is sodium bromide, which fully dissociates in water:
NaBr → Na+ + Br−
Hydrogen bromide, which is adiatomic molecule, takes on salt-like properties upon contact with water to give an ionic solution calledhydrobromic acid. The process is often described simplistically as involving formation of the hydronium salt of bromide:
One can test for a bromide ion by adding an oxidizer. One method uses diluteHNO3.
Balard and Löwig's method can be used to extract bromine from seawater and certain brines. For samples testing for sufficient bromide concentration, addition of chlorine produces bromine (Br2):[7]
From 1954 - 1977, the AustralianbiochemistShirley Andrews was researching safe ways to uselithium for the treatment ofmanic depressive illnesses while working at the Royal Park Psychiatric Hospital inVictoria. While conducting this research she discovered that bromide caused symptoms of mental illness, leading to a major reduction in its usage.[13]
Bromide compounds, especiallypotassium bromide, were frequently used as sedatives in the 19th and early 20th centuries. Their use in over-the-counter sedatives and headache remedies (such asBromo-Seltzer) in the United States extended to 1975 when bromides were withdrawn as ingredients due tochronic toxicity.[14] This use gave the word "bromide" its colloquial connotation of a comfortingcliché.[15]
It has been said that duringWorld War I, British soldiers were given bromide to curb their sexual urges.[16]
The bromide ion isantiepileptic and as bromide salt, is used in veterinary medicine in the US. The kidneys excrete bromide ions. The half-life of bromide in the human body (12 days) is long compared with many pharmaceuticals, making dosing challenging to adjust. (A new dose may require several months to reach equilibrium.) Bromide ion concentrations in thecerebrospinal fluid are about 30% of those in blood and are strongly influenced by the body's chloride intake and metabolism.[17]
Since bromide is still used in veterinary medicine in the United States, veterinary diagnostic labs can routinely measure blood bromide levels. However, this is not a conventional test in human medicine in the US since there are no FDA-approved uses for the bromide. Therapeutic bromide levels are measured in European countries likeGermany, where bromide is still used therapeutically in human epilepsy.
Bromoperoxidase enzymes use bromide (typically in seawater) to generate electrophilic brominating agents. Hundreds oforganobromine compounds are generated by this process. Notable examples are bromoform, thousands of tons of which are produced annually in this way. The historical dyeTyrian purple is produced by similar enzymatic reactions.[18]
In one specialized report, bromide is an essential cofactor in the peroxidising catalysis of sulfonimine crosslinks in collagen IV. Thispost-translational modification occurs in all animals and bromine is an essential trace element for humans.[19]
The average concentration of bromide in human blood in Queensland, Australia, is5.3±1.4 mg/L and varies with age and gender.[21] Much higher levels may indicate exposure to brominated chemicals. It is also found in seafood.
Anbar, A. D., Y. L. Yung, and F. P. Chavez (1996), Methyl bromide: Ocean sources, ocean sinks, and climate sensitivity, AGU Journals.
Foti, S. C., and Naval Ordnance Lab White Oak Md (1972), Concentration of Bromide Ions in Seawater by Isotopic Exchange with Mercurous Bromide, DTIC.
Gribble, G. W. (2000), The natural production of organobromine compounds, Environmental Science and Pollution Research, 7(1), 37–49,doi:10.1065/espr199910.002.
Leri A. (2012), The Chemistry of Bromine in Terrestrial and Marine Environments, Science Highlight.
Magazinovic, R. S., B. C. Nicholson, D. E. Mulcahy, and D. E. Davey (2004), Bromide levels in natural waters: its relationship to levels of both chloride and total dissolved solids and the implications for water treatment, Chemosphere, 57(4), 329–335,doi:10.1016/j.chemosphere.2004.04.056.
Pilinis, C., D. B. King, and E. S. Saltzman (1996), The oceans: A source or a sink of methyl bromide?, Geophysical Research Letters, 23(8), 817–820,doi:10.1029/96gl00424.
Stemmler, I., I. Hense, and B. Quack (2015), Marine sources of bromoform in the global open ocean – global patterns and emissions, Biogeosciences, 12(6), 1967–1981,doi:10.5194/bg-12-1967-2015.
Suzuki, A., Lim, L., Hiroi, T., & Takeuchi, T. (2006, March 20). Rapid determination of bromide in seawater samples by capillary ion chromatography using monolithic silica columns modified with cetyltrimethylammonium ion.
^Shannon, R. D. (1976). "Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides".Acta Crystallographica A.32 (5):751–767.Bibcode:1976AcCrA..32..751S.doi:10.1107/s0567739476001551.
^Michael J. Dagani, Henry J. Barda, Theodore J. Benya, David C. Sanders:Bromine Compounds, Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim.doi:10.1002/14356007.a04_405
^Tanaka, Yuki (2002)Japan's Comfort Women: Sexual slavery and prostitution during World War II and the US Occupation, Routledge, p. 175.ISBN0415194008.
^Goodman, L. S.; Gilman, A., eds. (1970). "10. Hypnotics and Sedatives".The Biological Basis of Therapeutics (4th ed.). London: Macmillan. p. 121.
^Gribble, Gordon W. (1999). "The diversity of naturally occurring organobromine compounds".Chemical Society Reviews.28 (5):335–346.doi:10.1039/a900201d.