He potassium bromide (KBr) is a haloide salt produced by a highly electropositive element, such as potassium (K), and highly electronegative, such as bromine (Br). The physical aspect is a white crystalline solid and is hygroscopic; that is, it absorbs water from the medium.
It was widely used in the pharmaceutical industry, specifically to prepare antiepileptic drugs, since the bromide ion is anticonvulsant. However, it is currently restricted to veterinary use. One way to obtain it is through the neutralization reaction, which occurs between hydrobromic acid and potassium hydroxide.
In the analysis of infrared samples, the use of KBr cells to contain the sample is very practical, due to its transparency that does not interact with the incident radiation.
Index
- 1 Structure (solid state)
- 2 Type of link
- 3 Physical and chemical properties
- 3.1 Physical
- 3.2 Chemicals
- 4 Applications
- 4.1 Epilepsy
- 4.2 Control of seizures in dogs
- 4.3 Spectroscopy
- 5 References
Structure (solid state)
Crystal structure: sodium chloride.
Coordination geometry: octahedral.
Bipolar moment: 10.41 D (gas).
Type of link
The KB has an ionic link. This type of bond is very common when an alkali metal is attached, which are those found in the IA family of the periodic table.
These are highly reactive elements because they have a great capacity to lose electrons and form cations, positively charged, with the elements of the VIIA family.
This group is known as halogen, which means salt former. They are very electronegative elements, so they attract electrons that are detached by the electropositive elements, forming anions that are negatively charged species.
These unions normally occur in aqueous media, since it is water that allows the formation of positive and negative ions through the process of dissociation.
In this type of link there is an electrostatic union between the charged species, so the force between them is not very high; hence its facility for dissociation in water.
The halogen completes its octet (eight electrons in its last energy level), which allows a greater stability in its internal energy.
Physical and chemical properties
Physical
Molar mass
119.01 g / moL
Density
2.75 g / mL
Melting point
734 ° C
Boiling point
1435 ° C
Water solubility
53.5 g / 100 mL (0 ° C)
This element conducts the electric current when it is in solution and crystallizes into rectangular prisms or cubes of pungent (sour) taste.
Chemicals
KBr is a stable compound at room temperature. It is characterized by having little reactivity with other substances.
It can react with other halogenated compounds such as chlorinated compounds, so that displacement of bromine by chlorine can occur.
With silver nitrate gives a yellowish white precipitate of silver bromide, which is widely used in photography for its sensitivity to light.
Although it is a compound of low reactivity, to manipulate it is necessary to wear nitrile gloves, protective masks, safety glasses, apron and covered shoe.
Applications
- Work as a diuretic and cathartic (laxative), but also has other uses in terms of health in the neural field.
- Before the appearance of phenobarbital, potassium bromide was used as a sedative and anticonvulsant. A study done by Sir William Gowes highlighted the importance of bromide as an effective compound to treat seizures. It should be noted that the bromide ion (Br - ) is responsible for the cure, regardless of the cation that accompanies it.
Epilepsy
In January 1874, Dr. Francis Anstie reported a case of epilepsy "Cured"by potassium bromide, in which the attacks were completely interrupted and remained absent long after the discontinuation of the medicine.
Anstie mentioned Dr. Hughlings Jackson, whose general experience in this topic was substantially in accordance with his own.
The combined experience of Anstie and Jackson must have spread to such a wide field that there were other cases where potassium bromide was used, in combination with cannabis indicates , and seemed to have positive effects in the treatment of epilepsy.
Control of seizures in dogs
In one study, the addition of potassium bromide (KBr) to the regimen of dogs with seizures decreased the severity of them.
The use of KBr allowed significant reductions in the doses of oral phenobarbital in 7 of 10 dogs, thus eliminating most of the behavioral abnormalities induced by drugs and reducing the risk of hepatotoxicity (toxicity in the liver).
It was concluded that KBr should be considered as a complementary therapy for dogs with severe seizure disorders that do not respond to high doses of phenobarbital alone.
Spectroscopy
Potassium bromide helps identify liquid compounds using infrared spectroscopy. This technique is used to identify the elemental composition of a substance.
Each molecule has a unique light absorbance profile within the infrared (IR) spectrum. This is determined by passing a beam of infrared light through the sample.
The liquid and solid samples are prepared to be studied by placing them between two plates of potassium bromide. The plates are transparent to infrared light and do not introduce any line on the spectra.
Potassium bromide salt plates are used because, being hygroscopic, they can attract water molecules.
References
- Perace, L, K., (1990), Potassioum bromide as an adjunct to phenobarbital for the management of uncontrolled seizures in dogs, Journal article: Progress in veterinary Neurology vol.No.1pp95-101.ref.1 Recuperado cabdirect.org
- Chevallier, M, A., (1854), Dictionary of alterations and falsifications of food, medicinal and commercial substances, with the indication of the means to recognize them. Madrid, Manuel Álvarez Printing House, Studios, 9
- Norton Manning, P., (April-1875), Journal of Mental Science , Bromide of Potassium in Epilepsy, Volume 21, Issue 93, 78-80, doi.org/101017/S0368315X00000086, online publication, February 2018