|Preferred IUPAC name
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||55.92 g/mol|
|Appearance||Colorless gas or liquid|
|Density||0.625 g/cm3 at −100 °C|
|Melting point||−161.5 °C (−258.7 °F; 111.6 K)|
|Boiling point||−20.2 °C (−4.4 °F; 253.0 K)|
|Slight, highly reactive|
|Main hazards||Spontaneously flammable in air; causes burns|
|GHS Signal word||Danger|
|H220, H250, H280, H314|
|P210, P222, P260, P264, P280, P301+330+331, P302+334, P303+361+353, P304+340, P305+351+338, P310, P321, P363, P370+378, P377, P381, P403, P405, P410+403, P422, P501|
|Flash point||Not applicable, pyrophoric gas|
|−40 °C (−40 °F; 233 K)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
As a liquid it is colourless. The strongest line in the infrared spectrum is at 1330 cm−1 followed by lines at 3010 cm−1 and 1185 cm−1.
Its melting point is −161.5 °C, and its boiling point is −20.2 °C.
Trimethylborane was first described in 1862 by Edward Frankland, who also mentioned its adduct with ammonia. Due to its dangerous nature the compound was no longer studied until 1921, when Alfred Stock and Friedrich Zeidler took advantage of the reaction between boron trichloride gas and dimethylzinc. Although the substance can be prepared using Grignard reagents the output is contaminated by unwanted products from the solvent. Trimethylborane can be made on a small scale with a 98% yield by reacting trimethylaluminium in hexane with boron tribromide in dibutyl ether as a solvent. Yet other methods are reacting tributyl borate with trimethylaluminium chloride, or potassium tetrafluoroborate with trimethylaluminium. Yet another method is to add boron trifluoride in ether to methyl magnesium iodide.
Trimethylborane spontaneously ignites in air if the concentration is high enough. It burns with a green flame producing soot. Slower oxidation with oxygen in a solvent or in the gas phase can produce dimethyltrioxadiboralane, which contains a ring of two boron and three oxygen atoms. However the major product is dimethylborylmethylperoxide, which rapidly decomposes to dimethoxymethylborane.
Trimethylborane is a strong Lewis acid. B(CH3)3 can form an adduct with ammonia: (NH3):B(CH3)3. as well as other Lewis bases. The Lewis acid properties of B(CH3)3 have been analyzed by the ECW model yielding EA= 2.90 and CA= 3.60. When trimethylborane forms an adduct with trimethylamine, steric repulsion between the methyl groups on the B and N results. The ECW model can provide a measure of this steric effect.
It reacts as a gas with trimethylphosphine to form a solid Lewis salt with a heat of formation of −41 kcal per mol. This adduct has a heat of sublimation of −24.6 kcal/mol. No reaction occurs with trimethylarsine or trimethylstibine.
Methyl lithium reacting with the Trimethylborane produces a tetramethylborate salt: LiB(CH3)4. The tetramethylborate ion has a negative charge and is isoelectronic with neopentane, tetramethylsilane, and the tetramethylammonium cation.
- "CHAPTER P-6. Applications to Specific Classes of Compounds". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 974. doi:10.1039/9781849733069-00648. ISBN 978-0-85404-182-4.
- Graner, G.; Hirota, E.; Iijima, T.; Kuchitsu, K.; Ramsay, D. A.; Vogt, J.; Vogt, N. (2001). "C3H9B Trimethylborane". Molecules containing Three or Four Carbon Atoms. Landolt-Börnstein - Group II Molecules and Radicals. 25C. p. 1. doi:10.1007/10688787_381. ISBN 978-3-540-66774-2.
- http://www.voltaix.com/images/doc/Msb000_TMB.pdf MSDS from Voltaix
- William S. Rees, Jr. and al (1990). Alvin P. Ginsberg (ed.). Trimethylborane. Inorganic Syntheses. 27. p. 339.
- E. Frankland (1862). "Ueber eine neue Reihe organischer Verbindungen, welche Bor enthalten". Justus Liebigs Ann. Chem. 124: 129–157. doi:10.1002/jlac.18621240102.
- R. Nishiyabu, Y. Kubo, T.D. James and J. S. Fossey (2011). "Boronic acid building blocks: tools for self assembly". Chem. Commun. 47 (4): 1124–1150. doi:10.1039/C0CC02921A. PMID 21113558.CS1 maint: multiple names: authors list (link)
- A. Stock and F. Zeidler (1921). "Zur Kenntnis des Bormethyls und Boräthyls". Ber. Dtsch. Chem. Ges. A/B. 54 (3): 531–541. doi:10.1002/cber.19210540321.
- Roland Köster, Paul Binger, Wilhelm V. Dahlhoff (1973). "A Convenient Preparation of Trimethylborane and Triethylborane". Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry. 3 (4): 359–367. doi:10.1080/00945717308057281.CS1 maint: multiple names: authors list (link)
- Donald Charles Mente (May 1975). "The Reactions of Trimethyl group Va Lewis Bases with simple Boron Lewis Acids" (PDF).
- Herbert Ellern (1968). Military and Civilian Pyrotechnics. Chemical Publishing Company. p. 24. CiteSeerX 10.1.1.137.1104.
- Barton, Lawrence; Crump, John M.; Wheatley, Jeffrey B. (June 1974). "Trioxadiborolanes from the oxidation of methyldiborane". Journal of Organometallic Chemistry. 72 (1): C1–C3. doi:10.1016/s0022-328x(00)82027-6.
- Gaylon S. Ross; et al. (2 October 1961). "Preparation of High Purity Trimethylborane" (PDF). Journal of Research of the National Bureau of Standards Section A. 66 (1).
- Georg Wittig in 1958