Arsine

Arsine

Discussion
Ask a question about 'Arsine'
Start a new discussion about 'Arsine'
Answer questions from other users
Full Discussion Forum
 
Encyclopedia
Arsine is the chemical compound
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 with the formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 As
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

H
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

3. This flammable, pyrophoric, and highly toxic gas is one of the simplest compounds of arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

. Despite its lethality, it finds applications in the semiconductor industry and for the synthesis of organoarsenic compound
Organoarsenic compound
Organoarsenic chemistry is the chemistry of compounds containing a chemical bond between arsenic and carbon. A few organoarsenic compounds, also called "organoarsenicals," are produced industrially with uses as insecticides, herbicides, and fungicides. In general these applications are declining in...

s.

General properties


At its standard state, arsine is a colorless, denser-than-air gas that is slightly soluble in water (20% at 20 C) and in many organic solvents as well. Whereas arsine itself is odorless, owing to its oxidation by air it is possible to smell a slight garlic
Garlic
Allium sativum, commonly known as garlic, is a species in the onion genus, Allium. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Dating back over 6,000 years, garlic is native to central Asia, and has long been a staple in the Mediterranean region, as well as a frequent...

 or fish-like scent when the compound is present at above about 0.5 ppm
Parts-per notation
In science and engineering, the parts-per notation is a set of pseudo units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement...

. This compound is generally regarded as stable, since at room temperature it decomposes only slowly. At temperatures of ca. 230 °C decomposition to arsenic and hydrogen is rapid. Several factors, such as humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...

, presence of light and certain catalysts (namely aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

) facilitate the rate of decomposition.

AsH3 is a pyramidal molecule with H–As–H angles of 91.8° and three equivalent As–H bonds, each of 1.519 Å
Ångström
The angstrom or ångström, is a unit of length equal to 1/10,000,000,000 of a meter . Its symbol is the Swedish letter Å....

 length. The term arsine is commonly used to describe a class of organoarsenic compounds of the formula AsH3−xRx, where R = aryl
Aryl
In the context of organic molecules, aryl refers to any functional group or substituent derived from an aromatic ring, be it phenyl, naphthyl, thienyl, indolyl, etc....

 or alkyl. For example, As(C6H5)3, called triphenylarsine
Triphenylarsine
Triphenylarsine is the chemical compound with the formula As3. This organoarsenic compound, often abbreviated AsPh3, is a colorless crystalline solid that is used as a ligand and a reagent in coordination chemistry and organic synthesis...

, is referred to as "an arsine."

Discovery and synthesis


AsH3 is generally prepared by the reaction of As3+ sources with H equivalents.
4 AsCl3 + 3 NaBH4 → 4 AsH3 + 3 NaCl + 3 BCl3

This type of reaction was employed in the discovery of arsine as reported in 1775 by Carl Scheele who reduced arsenic(III) oxide with zinc in the presence of acid. This reaction is a prelude to the Marsh test
Marsh test
The Marsh test is a highly sensitive method in the detection of arsenic, especially useful in the field of forensic toxicology when arsenic was used as a poison...

, described below.

Alternatively, sources of As3− react with protonic reagents to also produce this gas:
Zn3As2 + 6 H+ → 2 AsH3 + 3 Zn2+

Reactions


Our understanding of the chemical properties of AsH3 is well developed and can be anticipated based on an average of the behavior of PH3
Phosphine
Phosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...

 and SbH3
Stibine
Stibine is the chemical compound with the formula SbH3. This colourless gas is the principal covalent hydride of antimony and a heavy analogue of ammonia. The molecule is pyramidal with H–Sb–H angles of 91.7° and Sb–H distances of 1.707 Å...

.

Thermal decomposition


Typical for a heavy hydride (e.g., SbH3
Stibine
Stibine is the chemical compound with the formula SbH3. This colourless gas is the principal covalent hydride of antimony and a heavy analogue of ammonia. The molecule is pyramidal with H–Sb–H angles of 91.7° and Sb–H distances of 1.707 Å...

, H2Te, SnH4), AsH3 is unstable with respect to its elements. In other words, AsH3 is stable kinetically but not thermodynamically.
2 AsH3 → 3 H2 + 2 As

This decomposition reaction is the basis of the Marsh Test described below, which detects the metallic As.

Oxidation


Continuing the analogy to SbH3, AsH3 is readily oxidized by concentrated O2 or the dilute O2 concentration in air:
2 AsH3 + 3 O2 → As2O3 + 3 H2O

Arsine will react violently in presence of strong oxidizing agents, such as potassium permanganate
Potassium permanganate
Potassium permanganate is an inorganic chemical compound with the formula KMnO4. It is a salt consisting of K+ and MnO4− ions. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the...

, sodium hypochlorite or nitric acid
Nitric acid
Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...

.

Precursor to metallic derivatives


AsH3 is used as a precursor to metal complexes of "naked" (or "nearly naked") As. Illustrative is the dimanganese species [(C5H5)Mn(CO)2]2AsH, wherein the Mn2AsH core is planar.

Gutzeit test


A characteristic test for arsenic involves the reaction of AsH3 with Ag+, called the Gutzeit test for arsenic. Although this test has become obsolete in analytical chemistry
Analytical chemistry
Analytical chemistry is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials. Qualitative analysis gives an indication of the identity of the chemical species in the sample and quantitative analysis determines the amount of...

, the underlying reactions further illustrate the affinity of AsH3 for "soft" metal cations. In the Gutzeit test, AsH3 is generated by reduction of aqueous arsenic compounds, typically arsenite
Arsenous acid
Arsenous acid, also known as arsenious acid, is the inorganic compound with the formula H3AsO3. It is known to occur in aqueous solutions, but it has not been isolated as a pure material, although this fact does not detract from the significance of As3.-Properties:As3 is a pyramidal molecule...

s, with Zn in the presence of H2SO4. The evolved gaseous AsH3 is then exposed to AgNO3 either as powder or as a solution. With solid AgNO3, AsH3 reacts to produce yellow Ag4AsNO3, whereas AsH3 reacts with a solution of AgNO3 to give black Ag3As.

Acid-base reactions


The acidic properties of the As–H bond are often exploited. Thus, AsH3 can be deprotonated:
AsH3 + NaNH2 → NaAsH2 + NH3


Upon reaction with the aluminium trialkyls, AsH3 gives the trimeric [R2AlAsH2]3, where R = (CH3)3C. This reaction is relevant to the mechanism by which GaAs forms from AsH3 (see below).

AsH3 is generally considered non-basic, but it can be protonated by superacid
Superacid
According to the classical definition superacid is an acid with an acidity greater than that of 100% pure sulfuric acid, which has a Hammett acidity function of −12. According to the modern definition, superacid is a medium, in which the chemical potential of the proton is higher than in pure...

s to give isolable salts of the tetrahedral species [AsH4]+.

Reaction with halogen compounds


Reactions of arsine with the halogen
Halogen
The halogens or halogen elements are a series of nonmetal elements from Group 17 IUPAC Style of the periodic table, comprising fluorine , chlorine , bromine , iodine , and astatine...

s (fluorine
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...

 and chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

) or some of their compounds, such as nitrogen trichloride
Nitrogen trichloride
Nitrogen trichloride, also known as trichloramine, is the chemical compound with the formula NCl3. This yellow, oily, pungent-smelling liquid is most commonly encountered as a byproduct of chemical reactions between ammonia-derivatives and chlorine .In pure form, NCl3 is highly reactive...

, are extremely dangerous and can result in explosions.

Catenation


In contrast to the behavior of PH3, AsH3 does not form stable chains, although H2As–AsH2 and even H2As–As(H)–AsH2 have been detected. The diarsine is unstable above −100 °C.

Microelectronics applications


AsH3 is used in the synthesis of semiconducting materials related to microelectronics
Microelectronics
Microelectronics is a subfield of electronics. As the name suggests, microelectronics relates to the study and manufacture of very small electronic components. Usually, but not always, this means micrometre-scale or smaller,. These devices are made from semiconductors...

 and solid-state laser
Solid-state laser
A solid-state laser is a laser that uses a gain medium that is a solid, rather than a liquid such as in dye lasers or a gas as in gas lasers. Semiconductor-based lasers are also in the solid state, but are generally considered as a separate class from solid-state lasers .-Solid-state...

s. Related to P
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

, Arsenic is an n-dopant for silicon and germanium. More importantly, AsH3 is used to make the semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...

 GaAs
Gaas
Gaas is a commune in the Landes department in Aquitaine in south-western France....

 by chemical vapor deposition (CVD)
Chemical vapor deposition
Chemical vapor deposition is a chemical process used to produce high-purity, high-performance solid materials. The process is often used in the semiconductor industry to produce thin films. In a typical CVD process, the wafer is exposed to one or more volatile precursors, which react and/or...

 at 700–900 °C:
Ga(CH3)3 + AsH3 → GaAs + 3 CH4

For microelectronic applications, arsine can be provided via a sub-atmospheric gas source. In this type of gas package, the arsine is adsorbed on a solid microporous adsorbent inside a gas cylinder. This method allows the gas to be stored without pressure which significantly reduces the risk of an arsine gas leak from the cylinder. With this apparatus, arsine is obtained by applying vacuum to the gas cylinder valve outlet. For semiconductor manufacturing, this method is practical as these processes usually operate under high vacuum.

Chemical warfare


Since before WWII
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 AsH3 was proposed as a possible chemical warfare
Chemical warfare
Chemical warfare involves using the toxic properties of chemical substances as weapons. This type of warfare is distinct from Nuclear warfare and Biological warfare, which together make up NBC, the military acronym for Nuclear, Biological, and Chemical...

 weapon. The gas is colorless, almost odorless, and 2.5 times denser than air, as required for a blanketing effect sought in chemical warfare. It is also lethal in concentrations far lower than those required to smell its garlic
Garlic
Allium sativum, commonly known as garlic, is a species in the onion genus, Allium. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Dating back over 6,000 years, garlic is native to central Asia, and has long been a staple in the Mediterranean region, as well as a frequent...

-like scent. In spite of these characteristics, arsine was never officially used as a weapon, because of its high flammability and its lower efficacy when compared to the non-flammable alternative phosgene
Phosgene
Phosgene is the chemical compound with the formula COCl2. This colorless gas gained infamy as a chemical weapon during World War I. It is also a valued industrial reagent and building block in synthesis of pharmaceuticals and other organic compounds. In low concentrations, its odor resembles...

. On the other hand, several organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

s based on arsine, such as lewisite
Lewisite
Lewisite is an organoarsenic compound, specifically an arsine. It was once manufactured in the U.S. and Japan as a chemical weapon, acting as a vesicant and lung irritant...

 (β-chlorovinyldichloroarsine), adamsite
Adamsite
Adamsite or DM is an organic compound; technically, an arsenical diphenylaminechlorarsine, that can be used as a riot control agent. DM belongs to the group of chemical warfare agents known as vomiting agents or sneeze gases...

 (diphenylaminechloroarsine), Clark I
Diphenylchlorarsine
Diphenylchloroarsine is the organoarsenic compound with the formula 2AsCl. This odorless, toxic liquid was once used as harassing agent. It is also an intermediate in the preparation of other organoarsenic compounds...

 (diphenylchloroarsine) and Clark II
Diphenylcyanoarsine
Diphenylcyanoarsine, also called CLARK 2 by the Germans, was discovered in 1918 by Sturniolo and Bellinzoni and shortly thereafter used like the related Clark 1 gas by the Germans for chemical warfare in the First World War. The substance forms colourless, garlic-smelling crystals and causes...

 (diphenylcyanoarsine) have been effectively developed for use in chemical warfare.

Forensic science and the Marsh test


AsH3 is also well known in forensic science because it is a chemical intermediate in the detection of arsenic poisoning. The old (but extremely sensitive) Marsh test
Marsh test
The Marsh test is a highly sensitive method in the detection of arsenic, especially useful in the field of forensic toxicology when arsenic was used as a poison...

 generates AsH3 in the presence of arsenic. This procedure, developed around 1836 by James Marsh, is based upon treating an As-containing sample of a victim's body (typically the stomach) with As-free zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

 and dilute sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

: if the sample contains arsenic, gaseous arsine will form. The gas is swept into a glass tube and decomposed by means of heating around 250–300 °C. The presence of As is indicated by formation of a deposit in the heated part of the equipment. On the other hand, the appearance of a black mirror deposit in the cool part of the equipment indicates the presence of antimony (the highly unstable SbH3
Stibine
Stibine is the chemical compound with the formula SbH3. This colourless gas is the principal covalent hydride of antimony and a heavy analogue of ammonia. The molecule is pyramidal with H–Sb–H angles of 91.7° and Sb–H distances of 1.707 Å...

 decomposes even at low temperatures).

The Marsh test was widely used by the end of the 19th century and the start of the 20th; nowadays more sophisticated techniques such as atomic spectroscopy
Atomic spectroscopy
Atomic spectroscopy is the determination of elemental composition by its electromagnetic or mass spectrum. Atomic spectroscopy is closely related to other forms of spectroscopy. It can be divided by atomization source or by the type of spectroscopy used. In the latter case, the main division is...

, inductively coupled plasma
Inductively coupled plasma
An inductively coupled plasma is a type of plasma source in which the energy is supplied by electric currents which are produced by electromagnetic induction, that is, by time-varying magnetic fields.-Operation:...

 and x-ray fluorescence
X-ray fluorescence
X-ray fluorescence is the emission of characteristic "secondary" X-rays from a material that has been excited by bombarding with high-energy X-rays or gamma rays...

 analysis are employed in the forensic field. Though neutron activation
Neutron activation
Neutron activation is the process in which neutron radiation induces radioactivity in materials, and occurs when atomic nuclei capture free neutrons, becoming heavier and entering excited states. The excited nucleus often decays immediately by emitting particles such as neutrons, protons, or alpha...

 analysis was used to detect trace levels of arsenic in the mid 20th century it has fallen out of use in modern forensics.

Toxicology


For the toxicology of other arsenic compounds, see Arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

, Arsenic trioxide
Arsenic trioxide
Arsenic trioxide is the inorganic compound with the formula As2O3. This commercially important oxide of arsenic is the main precursor to other arsenic compounds, including organoarsenic compounds. Approximately 50,000 tonnes are produced annually...

, and Arsenicosis.

The toxicity of arsine is distinct from that of other arsenic compounds. The main route of exposure is by inhalation, although poisoning after skin contact has also been described. Arsine attacks haemoglobin in the red blood cell
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...

s, causing them to be destroyed by the body.

The first signs of exposure, which can take several hours to become apparent, are headache
Headache
A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...

s, vertigo
Vertigo (medical)
Vertigo is a type of dizziness, where there is a feeling of motion when one is stationary. The symptoms are due to a dysfunction of the vestibular system in the inner ear...

 and nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...

, followed by the symptoms of haemolytic anaemia (high levels of unconjugated bilirubin
Bilirubin
Bilirubin is the yellow breakdown product of normal heme catabolism. Heme is found in hemoglobin, a principal component of red blood cells. Bilirubin is excreted in bile and urine, and elevated levels may indicate certain diseases...

), haemoglobinuria and nephropathy
Nephropathy
Nephropathy refers to damage to or disease of the kidney. An older term for this is nephrosis.-Causes:Causes of nephropathy include administration of analgesics, xanthine oxidase deficiency, and long-term exposure to lead or its salts...

. In severe cases, the damage to the kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...

s can be long-lasting.

Exposure to arsine concentrations of 250 ppm is rapidly fatal: concentrations of 25–30 ppm are fatal for 30 min exposure, and concentrations of 10 ppm can be fatal at longer exposure times. Symptoms of poisoning appear after exposure to concentrations of 0.5 ppm. There is little information on the chronic toxicity of arsine, although it is reasonable to assume that, in common with other arsenic compounds, a long-term exposure could lead to arsenicosis.

See also

  • Arsenic
    Arsenic
    Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

  • Cacodylic acid
    Cacodylic acid
    Cacodylic acid is the chemical compound with the formula 2AsO2H. Derivatives of cacodylic acid, cacodylates, were frequently used as herbicides. For example, "Agent Blue," one of the chemicals used during the Vietnam War, is a mixture of cacodylic acid and sodium cacodylate...

  • Cacodyl oxide
    Cacodyl oxide
    Cacodyl oxide is a chemical compound of the formula [2As]2O. This organoarsenic compound is primarily of historical significance as it is sometimes considered to be the first organometallic compound synthesized in relatively pure form....

  • Devarda's alloy
    Devarda's alloy
    Devarda's alloy , is an alloy of aluminium , copper and zinc ....

    , also used to produce arsine in the lab
  • List of highly toxic gases
  • Marsh test
    Marsh test
    The Marsh test is a highly sensitive method in the detection of arsenic, especially useful in the field of forensic toxicology when arsenic was used as a poison...

     first used to analyse AsH3
  • James Marsh invented in 1836 the test bearing now his name
  • Stibine
    Stibine
    Stibine is the chemical compound with the formula SbH3. This colourless gas is the principal covalent hydride of antimony and a heavy analogue of ammonia. The molecule is pyramidal with H–Sb–H angles of 91.7° and Sb–H distances of 1.707 Å...


External links