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). Borate esters are prepared by heating boric acid 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 in brazing 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 acids, which are used in Suzuki couplings. These boronic acids are prepared via reaction of the trimethyl borate with Grignard reagents followed by hydrolysis:. 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 compounds MSDS for Trimethyl Borate WebBook page for BC3H9O3 Methyl esters Borate esters Solvents