Trimethyl borate is the organoboron compound with the formula B(OCH₃)₃. It is a colourless liquid that burns with a green flame. It is an intermediate in the preparation of sodium borohydride and is a popular reagent in organic chemistry. It is a weak Lewis acid (AN = 23, Gutmann-Beckett method). M.A. Beckett, G.C. Strickland, J.R. Holland, and K.S. Varma, "A convenient NMR method for the measurement of Lewis acidity at boron centres: correlation of reaction rates of Lewis acid initiated epoxide polymerizations with Lewis acidity", ''Polymer,'' 1996, 37, 4629–4631. doi: 10.1016/0032-3861(96)00323-0 Boratflamme

Borate ester In organic chemistry, borate esters are organoboron compounds which are conveniently prepared by the stoichiometric condensation reaction of boric acid with alcohols. There are two main classes of borate esters: orthoborates, and metaborates, . ...

s are prepared by heating

boric acid Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen borate or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolves ...

or related boron oxides with alcohols under conditions where water is removed.

Applications

Trimethyl borate is the main precursor to sodium borohydride by its reaction with sodium hydride: :4 NaH + B(OCH₃)₃ → NaBH₄ + 3 NaOCH₃ It is a gaseous

anti-oxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricants, ...

brazing Brazing is a metal-joining process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, with the filler metal having a lower melting point than the adjoining metal. Brazing differs from we ...

and solder flux. Otherwise, trimethyl borate has no announced commercial applications. It has been explored as a fire retardant, as well as being examined as an additive to some polymers.

Organic synthesis

It is a useful reagent in organic synthesis, as a precursor to

boronic acid A boronic acid is an organic compound related to boric acid () in which one of the three hydroxyl groups () is replaced by an alkyl or aryl group (represented by R in the general formula ). As a compound containing a carbon–boron bond, memb ...

s, which are used in Suzuki couplings. These boronic acids are prepared via reaction of the trimethyl borate with Grignard reagents followed by hydrolysis:.{{OrgSynth, author=R. L. Kidwell, M. Murphy, and S. D. Darling, year=1969, title=Phenols: 6-Methoxy-2-naphthol , volume=49, pages=90, collvol=10, collvolpages=80, prep=CV5P0918 : ArMgBr + B(OCH₃)₃ → MgBrOCH₃ + ArB(OCH₃)₂ :ArB(OCH₃)₂ + 2 H₂O → ArB(OH)₂ + 2 HOCH₃

References

External links

National Pollutant Inventory - Boron and compoundsMSDS for Trimethyl BorateWebBook page for BC₃H₉O₃
Methyl esters Borate esters Solvents