The arsine or arsano is a colorless and odorless gas, although in contact with air it acquires a slight smell of garlic and fish. The term arsine is not only used to name the compound AsH3, is also used to describe a set of organic arsenic (As) compounds of the formula AsH3-xRx.
In the formula, R represents alkyl or aryl compounds. For example, the compound As (C6H5)3 called triphenylarsine, it is known as an arsine.
However, in inorganic chemistry there is only one arsine: AsH3 (top image). The purple sphere represents the arsenic atom, and the white ones the hydrogen atoms. Although not shown, above the arsenic there is a pair of free electrons (··).
The toxic action of arsine occurs mainly by inhalation, as it crosses the alveolar wall and passes into the blood. There it acts producing hemolysis of erythrocytes, releasing hemoglobin that causes damage to the renal tubules that leads to renal dysfunction..
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As seen in the two upper images, the AsH3 it has a pyramidal structure. The As atom is located in the center of the pyramid, while the three H's in each of its vertices. The chemical hybridization of As should ordinarily be sp3 to adopt this geometry.
The image shows that the As-H bonds have a length of 1.519 Å, and the three H's are separated by an angle of 91.8º. This angle differs considerably from 107º for the ammonia molecule, NH3, indicating a rapprochement between the H.
Some chemists argue that this is due to the difference between the atomic radii between N and As.
Being the smallest N, the H are closer to each other, increasing their electrostatic repulsions, which tend to move them apart. Meanwhile, the As is larger, so the Hs are more distant from each other and the repulsions between them are less, so they tend to separate less..
-Arsine or arsano
-Arsenic hydride
-Arsenic trihydride
-Hydrogen arsenide
77.946 g / mol.
Colorless gas.
It is odorless, but in contact with the air it acquires a slight smell of garlic and fish. It is not an irritating gas, and in addition, it does not produce immediate symptoms; so people may be unaware of its presence.
-80.4ºF to 760mmHg (-62.5ºC).
-179ºF (-116ºC).
-62 ° C (-80 ° F, 211 ° K). Highly flammable gas.
In water 28 mg / 100 mL (practically insoluble in water). Slightly soluble in alcohol and alkali. Soluble in benzene and chloroform.
4.93 g / L of gas.
2.66 to 2.695 (relative to air taken as 1).
11,000 mmHg at 20 ºC.
When exposed to light, wet arsine decomposes rapidly, depositing shiny black arsenic.
When heated to decomposition, it emits highly toxic arsenic smoke, accompanied by hydrogen gas. It decomposes at 300ºC.
26.69 kJ / mol.
+ 66.4 kJ / mol.
In the previous section, mention was made of other accepted names for arsine. Considering it a binary hydride between arsenic and hydrogen, it can be named based on the systematic, stock and traditional nomenclatures.
In systematic nomenclature, they count the number of hydrogen atoms. Thus, its name comes to be: triarsenic hydride.
Its name according to the stock nomenclature is very similar, but adding its load with Roman numerals in parentheses: arsenic hydride (III).
And with respect to the traditional nomenclature, its name is arsina or arsano.
It can also be called hydrogen arsenide; however, it is not entirely correct, because it would imply assuming that arsenic is more electronegative than hydrogen and participates in the bond as As3-.
Arsine is used in the manufacture of semiconductor materials, used in microelectronics and solid-state lasers. It is used as a dopant for silicon and germanium. Arsine is used in the manufacture of the semiconductor GaAs.
The procedure used is chemical vapor deposition (CVD) at 700 - 900 ºC, according to the following reaction:
Ga (CH3)3 + AsH3 => GaAs + 3CH4
Arsine is a deadly gas, so it was thought of for use in chemical warfare. But it was never used officially as a chemical weapon, due to its high flammability and lower efficacy compared to other less flammable compounds..
However, some organic compounds derived from arsine, much more stable, have been shown to be of application in chemical warfare, for example Lewisite (β-chlorovinyldichloroarsine).
Arsine is a gas that ignites in air, but its more stable organic derivatives, for example AsR3 (R = alkyl or aryl groups), are used as binders in metal coordination chemistry.
The Ace (C6H5) is a soft binder and therefore is usually incorporated into metal complexes that have central atoms with low oxidation states (soft cations).
Its toxicity is such that at an airborne concentration of 250 ppm it is instantly lethal. May be fatal during 30 minute exposure at inhaled air concentration of 25 - 50 ppm.
Most of the toxic action of arsine occurs through inhalation. It is able to cross the alveolar wall and pass into the blood where it exerts its toxic action, which is carried out on erythrocytes and kidney function..
Arsine poisoning is manifested by disturbances of consciousness, shock, hematuria, jaundice, and kidney failure.
Arsine has several actions that are exerted on the wall of erythrocytes and hemoglobin. She promotes the release of the heme group from hemoglobin. Arsine is an indirect hemolytic agent, it acts by inhibiting the action of catalase.
This leads to the accumulation of hydrogen peroxide (HtwoORtwo), which causes the rupture of the erythrocyte membrane. On the other hand, arsine produces a decrease in the intracellular concentration of reduced glutathione (GSH), which contributes to the destruction of the erythrocyte membrane.
Massive hemolysis is fatal and is manifested by a reduction in the blood concentration of hemoglobin and hematocrit; increased serum hemoglobin and bilirubin concentration; and hematuria.
Renal failure is the consequence of the precipitation of hemoglobin in the form of casts in the renal tubules, observed at autopsies. Although, evidence has also been found, in vitro, of a direct toxic action of arsine on renal cell lines in culture.
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