|Molar mass||98.00 g/mol|
|Appearance||Colorless to pale yellow liquid|
|Melting point||−93 °C (−135 °F; 180 K)|
|Boiling point||95 °C (203 °F; 368 K)|
|N/A, Highly reactive|
|Main hazards||Spontaneously flammable in air; causes burns|
|R-phrases||R11 R14/15 R17 R19 R34 R35 R36/37|
|S-phrases||S6 S7/8 S16 S33 S36/37/39 S43A S45 S29|
|Flash point||< −20 °C (−4 °F; 253 K)|
|−20 °C (−4 °F; 253 K)|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Triethylborane (TEB), also called triethylboron, is an organoborane (a compound with a B-C bond). It is a colorless pyrophoric liquid. Its chemical formula is (C2H5)3B, abbreviated Et3B. It is soluble in organic solvents tetrahydrofuran and hexane.
Preparation and structure
- Et3Al + (MeO)3B → Et3B + (MeO)3Al
The molecule is monomeric, unlike H3B and Et3Al, which tend to dimerize. It has a planar BC3 core.
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, and its predecessor A-12 OXCART. 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. Conventional ignition plugs posed too high risk of a malfunction. It was used to start up each engine and to light the afterburners.
It reacts with metal enolates, yielding enoxytriethylborates that can be C-alkylated more selectively than in its absence. It is used in the Barton–McCombie deoxygenation reaction for deoxygenation of alcohols. In combination with lithium tri-tert-butoxyaluminum hydride it cleaves ethers. For example, THF is converted, after hydrolysis, to butanol. It also promotes certain variants of the Reformatskii reaction.
It is the precursor to the reducing agent Superhydride:
- LiH + Et3B → LiBHEt3
Triethylborane is strongly pyrophoric, igniting spontaneously in air, burning with an apple-green flame characteristic for boron compounds. Thus, it must be handled and stored in nitrogen or argon.
- Robert J. Brotherton, C. Joseph Weber, Clarence R. Guibert, John L. Little "Boron Compounds" in Ullmann's Encyclopedia of Industrial Chemistry 2000, Wiley-VCH. doi:10.1002/14356007.a04_309
- "Lockheed SR-71 Blackbird". March Field Air Museum. Retrieved 2009-05-05.
- "Lockheed SR-71 Blackbird Flight Manual". www.sr-71.org. Retrieved 2011-01-26.
- A. Young (2008). The Saturn V F-1 Engine: Powering Apollo Into History. Springer. p. 86. ISBN 0-387-09629-9.
- 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."
- Yoshinori Yamamoto, Takehiko Yoshimitsu, John L. Wood, Laura Nicole Schacherer "Triethylborane" Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt219.pub3