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| Identifiers | |
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3D model (JSmol) | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
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| ECHA InfoCard | 100.028.937 |
| RTECS number |
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| Properties | |
| KBr | |
| Molar mass | 119.002 g/mol |
| Appearance | white solid |
| Odor | odorless |
| Density | 2.74 g/cm3 |
| Melting point | 734 °C (1,353 °F; 1,007 K) |
| Boiling point | 1,435 °C (2,615 °F; 1,708 K) |
| 535 g/L (0 °C) 678 g/L (25 °C) 1020 g/L (100 °C) | |
| Solubility | very slightly soluble indiethyl ether |
| Solubility inglycerol | 217 g/L |
| Solubility inethanol | 47.6 g/L (80 °C) |
| −49.1×10−6 cm3/mol | |
Refractive index (nD) | 1.559 |
| Structure | |
| Sodium chloride(Face-centered cubic) | |
| octahedral | |
| 10.41 D (gas) | |
| Pharmacology | |
| QN03AX91 (WHO) | |
| Hazards | |
| GHS labelling: | |
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| Warning | |
| H319 | |
| P280,P305+P351+P338,P337+P313[1] | |
| NFPA 704 (fire diamond) | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 3070 mg/kg (oral, rat)[2] |
| Related compounds | |
Otheranions | Potassium fluoride Potassium chloride Potassium iodide |
Othercations | Lithium bromide Sodium bromide Rubidium bromide Caesium bromide Francium bromide |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Potassium bromide (KBr) is asalt, widely used as ananticonvulsant and asedative in the late 19th and early 20th centuries, with over-the-counter use extending to 1975 in the US. Its action is due to thebromide ion (sodium bromide is equally effective). Potassium bromide is used as a veterinary drug, in antiepileptic medication for dogs.Under standard conditions, potassium bromide is a white crystalline powder. It is freely soluble in water; it is not soluble inacetonitrile. In a dilute aqueous solution, potassium bromide tastes sweet, at higher concentrations it tastes bitter, and tastes salty when the concentration is even higher. These effects are mainly due to the properties of the potassium ion—sodium bromide tastes salty at any concentration. In high concentration, potassium bromide strongly irritates the gastric mucous membrane, causing nausea and sometimes vomiting (a typical effect of all soluble potassium salts).[citation needed]
Potassium bromide, a typicalionic salt, is fully dissociated and nearpH 7 inaqueous solution. It serves as a source of bromide ions. This reaction is important for the manufacture ofsilver bromide forphotographic film:
Aqueous bromideBr− also formscomplexes when reacted with some metal halides such ascopper(II) bromide:
A traditional method for the manufacture of KBr is the reaction ofpotassium carbonate with an iron(III,II) bromide,Fe3Br8, made by treating scrap iron under water with excessbromine:[4]
The anticonvulsant properties of potassium bromide were first noted by Sir Charles Locock at a meeting of theRoyal Medical and Chirurgical Society in 1857. Bromide can be regarded as the first effective medication forepilepsy. At the time, it was commonly thought that epilepsy was caused by masturbation.[6] Locock noted that bromide calmed sexual excitement and thought this was responsible for his success in treating seizures. In the latter half of the 19th century, potassium bromide was used for the calming of seizure and nervous disorders on an enormous scale, with the use by single hospitals being as much as several tons a year (the dose for a given person being a few grams per day).[6] By the beginning of the 20th century, the generic word had become so widely associated with being sedate that the term'bromide' came to mean a dull, sedate person or a boringplatitude uttered by such a person.[7]
There was not a better epilepsy drug untilphenobarbital in 1912. TheBritish Army has historically been claimed to lace soldiers'tea with bromide to quell sexual arousal and in the Victorian era prisoners in England were compulsorily dosed with the chemical.[8][9]
Bromide compounds, especiallysodium bromide, remained in over-the-counter sedatives and headache remedies (such as the original formulation ofBromo-Seltzer) in the US until 1975, when bromides were outlawed in all over-the-counter medicines, due to chronic toxicity.[10] Bromide's exceedingly longbiological half-life made it difficult to dose without side effects. Medical use of bromides for humans in the US was discontinued at this time, as many better and shorter-acting sedatives were known by then.
Potassium bromide is still used in veterinary medicine to treatepilepsy in dogs, either as first-line treatment or in addition to phenobarbital, when seizures are not adequately controlled with phenobarbital alone.[5] Use of bromide in cats is limited because it carries a substantial risk of causing lung inflammation (pneumonitis) in them. Why bromides should cause such inflammation in cats, but not in dogs, is not clear.[11]
The use of bromide as a treatment drug for animals means that veterinary medical diagnostic laboratories are able as a matter of routine to measure serum levels of bromide on order of a veterinarian, whereas human medical diagnostic labs in the US do not measure bromide as a routine test.
Potassium bromide is not approved by the USFood and Drug Administration (FDA) for use in humans to control seizures. In Germany, it is still approved as an antiepileptic drug for humans, particularly children and adolescents.[12] These indications include severe forms of generalized tonic-clonic seizures, early-childhood-related tonic–clonic seizures, and also severe myoclonic seizures during childhood. Adults who have reacted positively to the drug during childhood/adolescence may continue treatment. Potassium bromide tablets are sold under the brand nameDibro-Be mono (Rx-only). The drug has almost complete bioavailability, but the bromide ion has a relatively long biological half-life of 12 days in the blood,[6] making bromide salts difficult to adjust and dose. Bromide is not known to interfere with the absorption or excretion of any other anticonvulsant, though it does have strong interactions with chloride in the body, the normal body uptake and excretion of which strongly influences bromide's excretion.[6]
The therapeutic index (ratio of effectiveness to toxicity) for bromide is small. As with other antiepileptics, sometimes even therapeutic doses (3 to 5 grams per day, taking 6 to 8 weeks to reach stable levels) may give rise to intoxication. Often indistinguishable from 'expected' side-effects, these include:
Potassium bromide is transparent from the nearultraviolet to long-waveinfraredwavelengths (0.25-25 μm) and has no significantoptical absorption lines in its high transmission region.It is used widely as infrared optical windows and components for general spectroscopy because of its wide spectral range. Ininfrared spectroscopy, samples are analyzed by grinding with powdered potassium bromide and pressing into a disc. Alternatively, samples may be analyzed as a liquid film (neat, as a solution, or in a mull withNujol) between two polished potassium bromide discs.[13]
Due to its high solubility andhygroscopic nature it must be kept in a dry environment. Therefractive index is about 1.55 at 1.0 μm.
In addition to manufacture of silver bromide, potassium bromide is used as a restrainer inblack and whitedeveloper formulas. It improves differentiation between exposed and unexposed crystals of silver halide, and thus reduces fog.[14]
The Great American Fraud.
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