Triethylborane
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| Names | |||
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| IUPAC name
Triethylborane
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| Other names
triethylborine, triethylboron
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| Identifiers | |||
3D model (JSmol)
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| ChemSpider | |||
| ECHA InfoCard | 100.002.383 | ||
| EC Number |
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |||
| C6H15B | |||
| Molar mass | 98.00 g/mol | ||
| Appearance | Colorless to pale yellow liquid | ||
| Density | 0.677 g/cm3 | ||
| Melting point | −93 °C (−135 °F; 180 K) | ||
| Boiling point | 95 °C (203 °F; 368 K) | ||
| N/A, Highly reactive | |||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards
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Spontaneously flammable in air; causes burns | ||
| Related compounds | |||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Triethylborane (TEB), also called triethylborine and triethylboron, is an organoborane (an organometallic compound), a near-colorless to yellowish transparent liquid with pungent ether-like odor.[citation needed] Its chemical formula can be written as C6H15B, or (CH3CH2)3B, or (C2H5)3B, or Et3B.
Triethylborane is strongly pyrophoric, igniting spontaneously in air. It burns intensely with a very hot flame. The color of the flame is apple-green, which is characteristic for boron compounds. Its fire should not be extinguished with water; a carbon dioxide or dry powder extinguisher (e.g. Purple K) would be more suitable. Its vapors may cause flash fire.[1]
It is soluble in tetrahydrofuran and hexane, and is not pyrophoric when in solution.[citation needed] However the solution can slowly react with atmospheric moisture. If the TEB solutions are exposed to air for prolonged time, unstable organic peroxides may form, with the presence of cationic initiators leading to polymerization. It is toxic to peripheral nervous system, kidneys and testes. Triethylborane is extremely corrosive. Some sources incorrectly refer to this chemical as tetraethylborane.[2]
Applications
Triethylborane was used to ignite the JP-7 fuel in the Pratt & Whitney J58 turbojet/ramjet engines powering the Lockheed SR-71 Blackbird spy plane,[3] and its predecessor A-12 OXCART. Mixed with 10-15% triethylaluminium, it was also used before lift-off to ignite the F-1 Engines on the Saturn V Rocket.[4] Triethylborane is suitable for this because of its pyrophoric properties, especially the fact that it burns with very high temperature. It was chosen as an ignition method for reliability reasons, and in the case of the Blackbird, because the JP-7 fuel has very low volatility and is difficult to ignite. Classical ignition plugs posed too high risk of a malfunction. It was used to start up each engine and to light the afterburners.[5]
The SpaceX Falcon 9 heavy-lift rocket uses a triethylaluminum-triethylborane mixture as a first-stage ignitor.[6]
Industrially, triethylborane is used as an initiator in radical reactions, where it is effective even at low temperatures. As an initiator, it can replace some organotin compounds. It reacts with metal enolates, yielding enoxytriethylborates with use in selective alkylation and aldol reactions. It is also used in reduction bond cleavage with lithium tri-tert-butoxyaluminohydride, in preparation of various boron compounds, deoxygenation of primary and secondary alcohols, rapid determination of -OH groups in organic compounds, dehydration of salt and sugar hydrates, determination of water content in crystalline hydrate compounds, in a variant of Reformatskii reaction, and has a range of other uses in organoborane chemistry.[citation needed]
Triethylborane is used in vapor deposition techniques as a boron source. Examples are the plasma deposition of boron-containing hard carbon films, silicon nitride-boron nitride films, and for doping of diamond film with boron.[citation needed] Other boron precursors used for such applications are e.g. trimethylborane, boron trifluoride, diborane, and decaborane.
Sodium tetraethylborate (NaTEB), a triethylborane derivative, is used as a powerful ethylation agent.
See also
References
- ^ http://caligula.bcs.deakin.edu.au/bcs_admin/msds/ChemicalSummary.asp?ID=3566 MSDS
- ^ Herb Wolfe. "SR-71" (PDF). Tetraethylborane is used for the aviation fuel.
- ^ "Lockheed SR-71 Blackbird". March Field Air Museum. Retrieved 2009-05-05.
- ^ A. Young (2008). The Saturn V F-1 Engine: Powering Apollo Into History. Springer. p. 86. ISBN 0-387-09629-9.
- ^ "Lockheed SR-71 Blackbird Flight Manual". www.sr-71.org. Retrieved 2011-01-26.
- ^ Mission Status Center, June 2, 2010, 1905 GMT, SpaceflightNow, accessed 2010-06-02, Quotation: "The flanges will link the rocket with ground storage tanks containing liquid oxygen, kerosene fuel, helium, gaseous nitrogen and the first stage ignitor source called triethylaluminum-triethylborane, better known as TEA-TAB."