Disilane
Encyclopedia
Disilane is a chemical compound
with chemical formula
Si2H6 that was identified in 1902 by Henri Moissan
and Samuel Smiles (1877–1953). Moissan and Smiles reported disilane as being among the products formed by the action of dilute acids on metal silicides. Although these reactions had been previously investigated by Friedrich Woehler and Heinrich Buff between 1857 and 1858, Moissan and Smiles were the first to explicitly identify disilane. They referred to disilane as silicoethane. Higher members of the homologous series SinH2n+2 formed in these reactions were subsequently identified by Carl Somiesky (sometimes spelled "Karl Somieski") and Alfred Stock
.
At standard temperature and pressure
, disilane is a colourless, acrid gas. Disilane and ethane
have similar structures, although disilane is much more reactive. Other compounds of the general formula Si2X6 (X = hydride, halide, alkyl, aryl, and mixtures of these groups) are called disilanes.
of magnesium silicide
. This reaction produces silane
, disilane, and even trisilane. The method has been abandoned for the production of silane, but it remains viable for generating disilane. The presence of traces of disilane is responsible for the spontaneous flammability of silane produced by hydrolysis by this method (analogously diphosphine
is often the spontaneously pyrophoric contaminant in samples of phosphine
).
US Patent 4,604,274 discloses a process for manufacture of disilane via radiation irritation of silane.
The Direct process
, by which most organosilicon compounds are produced industrially, generates a non-volatile residue that consists of significant amounts of disilanes, e.g., CH3Si2H5-xClx.
process is relevant to the manufacture of photovoltaic devices. Specifically it is utilized in the production of silicon wafers
.
More generally, diorganosilanes are produced by reductive coupling of silyl chlorides, e.g.
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 chemical formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
Si2H6 that was identified in 1902 by Henri Moissan
Henri Moissan
Ferdinand Frederick Henri Moissan was a French chemist who won the 1906 Nobel Prize in Chemistry for his work in isolating fluorine from its compounds.-Biography:...
and Samuel Smiles (1877–1953). Moissan and Smiles reported disilane as being among the products formed by the action of dilute acids on metal silicides. Although these reactions had been previously investigated by Friedrich Woehler and Heinrich Buff between 1857 and 1858, Moissan and Smiles were the first to explicitly identify disilane. They referred to disilane as silicoethane. Higher members of the homologous series SinH2n+2 formed in these reactions were subsequently identified by Carl Somiesky (sometimes spelled "Karl Somieski") and Alfred Stock
Alfred Stock
Alfred Stock was a German inorganic chemist. He did pioneering research on the hydrides of boron and silicon, coordination chemistry, mercury, and mercury poisoning...
.
At standard temperature and pressure
Standard conditions for temperature and pressure
Standard condition for temperature and pressure are standard sets of conditions for experimental measurements established to allow comparisons to be made between different sets of data...
, disilane is a colourless, acrid gas. Disilane and ethane
Ethane
Ethane is a chemical compound with chemical formula C2H6. It is the only two-carbon alkane that is an aliphatic hydrocarbon. At standard temperature and pressure, ethane is a colorless, odorless gas....
have similar structures, although disilane is much more reactive. Other compounds of the general formula Si2X6 (X = hydride, halide, alkyl, aryl, and mixtures of these groups) are called disilanes.
Synthesis
Disilane is usually prepared by the hydrolysisHydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
of magnesium silicide
Magnesium silicide
Magnesium silicide, Mg2Si, is an inorganic compound consisting of magnesium and silicon. As a powder magnesium silicide is dark blue or slightly purple in color. Silicon dioxide, SiO2, found in sand and glass, when heated with magnesium forms magnesium oxide, and, if an excess of magnesium is...
. This reaction produces silane
Silane
Silane is a toxic, extremely flammable chemical compound with chemical formula SiH4. In 1857, the German chemists and Friedrich Woehler discovered silane among the products formed by the action of hydrochloric acid on aluminum silicide, which they had previously prepared...
, disilane, and even trisilane. The method has been abandoned for the production of silane, but it remains viable for generating disilane. The presence of traces of disilane is responsible for the spontaneous flammability of silane produced by hydrolysis by this method (analogously diphosphine
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...
is often the spontaneously pyrophoric contaminant in samples of phosphine
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...
).
US Patent 4,604,274 discloses a process for manufacture of disilane via radiation irritation of silane.
The Direct process
Direct process
The Direct Process, also called the Direct Synthesis, Rochow Process, and Müller-Rochow Process is the most common technology for preparing organosilicon compounds on an industrial scale. It was first reported independently by Eugene G. Rochow and Richard Müller in the 1940s...
, by which most organosilicon compounds are produced industrially, generates a non-volatile residue that consists of significant amounts of disilanes, e.g., CH3Si2H5-xClx.
Applications and reactions
Disilane and silane thermally decompose around 640 °C, depositing amorphous silicon. This chemical vapor depositionChemical 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...
process is relevant to the manufacture of photovoltaic devices. Specifically it is utilized in the production of silicon wafers
Wafer (electronics)
A wafer is a thin slice of semiconductor material, such as a silicon crystal, used in the fabrication of integrated circuits and other microdevices...
.
More generally, diorganosilanes are produced by reductive coupling of silyl chlorides, e.g.
- 2 (CH3)3SiCl + 2 Na → (CH3)3Si-Si(CH3)3 + 2 NaCl