Difference between revisions of "Silane" - New World Encyclopedia
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! {{chembox header}} | Silane | ! {{chembox header}} | Silane | ||
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| Other names | | Other names | ||
| − | | Silicon tetrahydride<br>Silicon hydride<br>Monosilane<br>Silicane | + | | Silicon tetrahydride<br/>Silicon hydride<br/>Monosilane<br/>Silicane |
|- | |- | ||
| [[Chemical formula|Molecular formula]] | | [[Chemical formula|Molecular formula]] | ||
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| [[Density]] and [[Phase (matter)|phase]] | | [[Density]] and [[Phase (matter)|phase]] | ||
| − | | ? kg m<sup>−3</sup> (solid)<br>0.7 g/ml (liquid)<br> 1.342 g L<sup>−1</sup> (gas) | + | | ? kg m<sup>−3</sup> (solid)<br/>0.7 g/ml (liquid)<br/> 1.342 g L<sup>−1</sup> (gas) |
|- | |- | ||
| [[Solubility]] in [[Water_(molecule)|water]] | | [[Solubility]] in [[Water_(molecule)|water]] | ||
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| Main [[Worker safety and health|hazard]]s | | Main [[Worker safety and health|hazard]]s | ||
| − | | low toxicity,<br>avoid exposure to skin,<br>irritant, may cause<br>redness and swelling | + | | low toxicity,<br/>avoid exposure to skin,<br/>irritant, may cause<br/>redness and swelling |
|- | |- | ||
| [[NFPA 704]] | | [[NFPA 704]] | ||
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| Related silanes | | Related silanes | ||
| − | | [[disilane]]<br>[[trisilane]]<br>[[tetrasilane]]<br>[[cyclosilane]] | + | | [[disilane]]<br/>[[trisilane]]<br/>[[tetrasilane]]<br/>[[cyclosilane]] |
|- | |- | ||
| Related hydrides | | Related hydrides | ||
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| − | + | '''Silane''' is a [[chemical compound]] with [[chemical formula]] [[silicon|Si]][[hydrogen|H]]<sub>4</sub>. It is the silicon analog of [[methane]]. At [[room temperature]], silane is a gas, and is [[pyrophoric]]--that is, it undergoes spontaneous [[combustion]] in [[air]], without the need for external ignition. However, one school of thought holds that silane itself is stable and that the natural formation of larger silanes during production causes its pyrophoricity. Above 420°C, silane decomposes into silicon and hydrogen; it can therefore be used in the [[chemical vapor deposition]] of silicon. | |
| − | + | In a more general definition, a silane is any silicon analog of an [[alkane]] hydrocarbon. Silanes consist of a chain of silicon atoms [[covalent bond|covalently bound]] to hydrogen atoms. The general formula of a silane is Si<sub>n</sub>H<sub>2n+2</sub>. Silanes tend to be less stable than their carbon analogs because the Si-Si [[chemical bond|bond]] has a strength slightly lower than the C-C bond. [[Oxygen]] decomposes silanes easily, because the silicon-oxygen bond is quite stable. | |
| − | + | == Nomenclature of different structures == | |
| − | + | There are certain rules for naming silanes. For instance, depending on the number of silicon atoms in each molecule, the word silane is preceded by a numerical prefix, such as di, tri, tetra, and so forth. Thus, Si<sub>2</sub>H<sub>6</sub> is [[disilane]], and Si<sub>3</sub>H<sub>8</sub> is trisilane. SiH<sub>4</sub> is simply silane, without a prefix. | |
| − | Silanes | + | In an alternative system of nomenclature, silanes may be named in a manner similar to other inorganic compounds. For instance, silane is called silicon tetrahydride. However, with longer silanes, this system becomes cumbersome. |
| + | |||
| + | A [[cyclosilane]] is a silane with a ring structure, just as a [[cycloalkane]] is an alkane with a ring structure. | ||
| + | |||
| + | Some silanes have branched structures. The [[radical (chemistry)|radical]] ·SiH<sub>3</sub> is termed silyl, ·Si<sub>2</sub>H<sub>5</sub> is disilanyl, and so on. Trisilane with a silyl group attached to the middle silicon is named silyltrisilane. The nomenclature parallels that of [[alkyl]] radicals. | ||
| + | |||
| + | Silanes may also carry certain functional groups, just as alkanes do. For instance, if a [[hydroxyl group]] (OH) is attached to a silane, it is called a [[silanol]]. There is (at least in principle) a silicon analog for all carbon alkanes. | ||
== Production == | == Production == | ||
| Line 133: | Line 139: | ||
Several industrial and medical applications exist for silanes. For instance, silanes are used as coupling agents to adhere [[fiberglass|glass fiber]]s to a [[polymer]] matrix, stabilizing the [[composite material]]. They can also be used to couple a bio-inert layer on a [[titanium]] [[prosthesis|implant]]. Other applications include water repellents, [[masonry]] protection, control of [[graffiti]],<ref>[http://www.protectosil.com/protectosil/en/otherregions/graffiticontrol/default Graffiti protection systems]</ref> applying [[polycrystalline silicon]] layers on silicon wafers when manufacturing semiconductors, and sealants. | Several industrial and medical applications exist for silanes. For instance, silanes are used as coupling agents to adhere [[fiberglass|glass fiber]]s to a [[polymer]] matrix, stabilizing the [[composite material]]. They can also be used to couple a bio-inert layer on a [[titanium]] [[prosthesis|implant]]. Other applications include water repellents, [[masonry]] protection, control of [[graffiti]],<ref>[http://www.protectosil.com/protectosil/en/otherregions/graffiticontrol/default Graffiti protection systems]</ref> applying [[polycrystalline silicon]] layers on silicon wafers when manufacturing semiconductors, and sealants. | ||
| − | Silane and similar compounds containing Si-H | + | Silane and similar compounds containing Si-H bonds are used as reducing agents in organic and organometallic chemistry.<ref>[http://www.organic-chemistry.org/chemicals/reductions/silanes.shtm Reductions of organic compounds using silanes]</ref> |
| + | |||
| + | ==See also== | ||
| + | |||
| + | * [[Alkane]] | ||
| + | * [[Functional group]] | ||
| + | * [[Methane]] | ||
| + | * [[Silicon]] | ||
| − | == | + | == Notes == |
<references/> | <references/> | ||
| − | == | + | ==References== |
| − | |||
==External links== | ==External links== | ||
| − | |||
Revision as of 00:59, 23 August 2007
| Silane | |
|---|---|
 
| |
| General | |
| Systematic name | Silane |
| Other names | Silicon tetrahydride Silicon hydride Monosilane Silicane |
| Molecular formula | SiH4 |
| Molar mass | 32.12 g mol−1 |
| Appearance | Colourless gas |
| CAS number | [7803-62-5] |
| Properties | |
| Density and phase | ? kg m−3 (solid) 0.7 g/ml (liquid) 1.342 g L−1 (gas) |
| Solubility in water | Insoluble |
| Melting point | 88 K (−185°C) |
| Boiling point | 161 K (−112°C) |
| ΔfH0solid | -1615 kJ mol−1 |
| S0solid | 283 J mol−1 K−1 |
| Structure | |
| Molecular shape | tetrahedral |
| Dipole moment | 0 D |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | low toxicity, avoid exposure to skin, irritant, may cause redness and swelling |
| NFPA 704 |
4
1
3
|
| Flash point | N/A |
| Autoignition temperature | 294 K (21°C) |
| R/S statement | R: ? S: ? |
| UN number | 2203 |
| RTECS number | VV1400000 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related silanes | disilane trisilane tetrasilane cyclosilane |
| Related hydrides | methane |
| Related compounds | disilene |
| Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references | |
Silane is a chemical compound with chemical formula SiH4. It is the silicon analog of methane. At room temperature, silane is a gas, and is pyrophoric—that is, it undergoes spontaneous combustion in air, without the need for external ignition. However, one school of thought holds that silane itself is stable and that the natural formation of larger silanes during production causes its pyrophoricity. Above 420°C, silane decomposes into silicon and hydrogen; it can therefore be used in the chemical vapor deposition of silicon.
In a more general definition, a silane is any silicon analog of an alkane hydrocarbon. Silanes consist of a chain of silicon atoms covalently bound to hydrogen atoms. The general formula of a silane is SinH2n+2. Silanes tend to be less stable than their carbon analogs because the Si-Si bond has a strength slightly lower than the C-C bond. Oxygen decomposes silanes easily, because the silicon-oxygen bond is quite stable.
Nomenclature of different structures
There are certain rules for naming silanes. For instance, depending on the number of silicon atoms in each molecule, the word silane is preceded by a numerical prefix, such as di, tri, tetra, and so forth. Thus, Si2H6 is disilane, and Si3H8 is trisilane. SiH4 is simply silane, without a prefix.
In an alternative system of nomenclature, silanes may be named in a manner similar to other inorganic compounds. For instance, silane is called silicon tetrahydride. However, with longer silanes, this system becomes cumbersome.
A cyclosilane is a silane with a ring structure, just as a cycloalkane is an alkane with a ring structure.
Some silanes have branched structures. The radical ·SiH3 is termed silyl, ·Si2H5 is disilanyl, and so on. Trisilane with a silyl group attached to the middle silicon is named silyltrisilane. The nomenclature parallels that of alkyl radicals.
Silanes may also carry certain functional groups, just as alkanes do. For instance, if a hydroxyl group (OH) is attached to a silane, it is called a silanol. There is (at least in principle) a silicon analog for all carbon alkanes.
Production
Industrially, silane is produced from metallurgical grade silicon in a two-step process. In the first step, powdered silicon is reacted with hydrochloric acid at about 300 °C to produce trichlorosilane, HSiCl3, along with hydrogen gas, according to the chemical equation:
- Si + 3HCl → HSiCl3 + H2
The trichlorosilane is then boiled on a resinous bed containing a catalyst which promotes its disproportionation to silane and silicon tetrachloride according to the chemical equation:
- 4HSiCl3 → SiH4 + 3SiCl4
The most commonly used catalysts for this process are metal halides, particularly aluminium chloride.
Applications
Several industrial and medical applications exist for silanes. For instance, silanes are used as coupling agents to adhere glass fibers to a polymer matrix, stabilizing the composite material. They can also be used to couple a bio-inert layer on a titanium implant. Other applications include water repellents, masonry protection, control of graffiti,[1] applying polycrystalline silicon layers on silicon wafers when manufacturing semiconductors, and sealants.
Silane and similar compounds containing Si-H bonds are used as reducing agents in organic and organometallic chemistry.[2]
See also
Notes
ReferencesISBN links support NWE through referral fees
External links
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