Trimethyl borate
Chemical compound
From Wikipedia, the free encyclopedia
Trimethyl borate is the organoboron compound with the formula B(OCH3)3. It is a colourless liquid that burns with a green flame.[1] 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).[2]
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| Names | |
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| IUPAC name
Trimethyl borate | |
| Other names
Trimethoxyborane | |
| Identifiers | |
3D model (JSmol) |
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.004.063 |
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PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C3H9BO3 | |
| Molar mass | 103.91 g·mol−1 |
| Appearance | colourless liquid |
| Density | 0.932 g/ml |
| Melting point | −34 °C (−29 °F; 239 K) |
| Boiling point | 68 to 69 °C (154 to 156 °F; 341 to 342 K) |
| decomposition | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards |
flammable |
| Related compounds | |
Other cations |
Trimethyl phosphite Tetramethyl orthosilicate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Borate esters are prepared by heating boric acid or related boron oxides with alcohols under conditions where water is removed by azeotropic distillation. [1]
Applications
Trimethyl borate is the main precursor to sodium borohydride by its reaction with sodium hydride in the Brown-Schlesinger process:
- 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.[1]
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:.[3][4]
- ArMgBr + B(OCH3)3 → MgBrOCH3 + ArB(OCH3)2
- ArB(OCH3)2 + 2 H2O → ArB(OH)2 + 2 HOCH3