Arsenic trihydride

Arsenic Trihydride also known as Arsine is a chemical compound with the formula AsH3. This colorless gas is one of the simplest compounds of arsenic. Despite its lethality, it finds some applications in the semiconductor industry and for the synthesis of organoarsenic compounds. The term arsine is commonly used to describe a class of organoarsenic compounds of the formula AsH3−xRx, where R = aryl or alkyl. For example, As(C6H5)3, called triphenylarsine, is referred to as "an arsine".

History

Arsenic trihydride was first synthesized in 1775 by Carl Wilhelm Scheele, a Swedish chemist, who termed it as "arsenited hydrogen". The gas was given its current name "arsine" by Antoine Lavoisier, in his work Elements of Chemistry, published in 1789.

Properties

Arsenic trihydride is a pyramidal molecule with H–As–H angles of 91.8° and three equivalent As–H bonds, each of 1.519 Å length. The AsH3 molecule is non-polar and thus interacts only weakly with polar solvents. Because of this non-reactivity, AsH3 is readily able to escape from water.

Production and Synthesis

Arsenic trihydride can be generated via several methods. The most common method is the reduction of arsenic by acid in the presence of a reducing agent, typically a metal such as zinc or aluminium. Another method involves the reaction of arsenic with hydrogen gas, although this process is less common due to the high temperature required.

Applications

Despite its toxicity, arsenic trihydride has found use in the semiconductor industry where it is used as a dopant in the production of gallium arsenide semiconductors. It is also used in the synthesis of organoarsenic compounds.

Safety and Toxicity

Arsenic trihydride is highly toxic and can be lethal if inhaled. It is a potent hemolytic agent, meaning it can cause the destruction of red blood cells. Symptoms of arsenic trihydride poisoning include headache, confusion, drowsiness, and in severe cases, seizures and death.

See Also

• Arsenic
• Hydride
• Semiconductor industry
• Organoarsenic chemistry