Trimethyl borate

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Trimethyl borate
Structural formula of trimethyl borate.svg
Trimethyl-borate-3D-vdW.png
Names
IUPAC name
Trimethyl borate
Other names
Trimethoxyborane
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.004.063 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 204-468-9
PubChem CID
UNII
  • InChI=1S/C3H9BO3/c1-5-4(6-2)7-3/h1-3H3 Yes check.svgY
    Key: WRECIMRULFAWHA-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C3H9BO3/c1-5-4(6-2)7-3/h1-3H3
    Key: WRECIMRULFAWHA-UHFFFAOYAY
  • O(B(OC)OC)C
Properties
C3H9BO3
Molar mass 103.91 g·mol−1
Appearancecolourless 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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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]

Contents

This chemical is quite flammable and burns with a green flame Boratflamme.jpg
This chemical is quite flammable and burns with a green flame

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

References

  1. 1 2 3 Robert J. Brotherton; C. Joseph Weber; Clarence R. Guibert; John L. Little (2000). "Boron Compounds". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. ISBN   978-3-527-30673-2.
  2. ↑ Beckett, M. A.; Strickland, G. C.; Holland, J. R.; Varma, K. S. (September 1996). "A convenient n.m.r. method for the measurement of Lewis acidity at boron centres: correlation of reaction rates of Lewis acid initiated epoxide polymerizations with Lewis acidity". Polymer. 37 (20): 4629–4631. doi:10.1016/0032-3861(96)00323-0.
  3. ↑ Ishihara, Kazuaki; Ohara, Suguru; Yamamoto, Hisashi (2002). "3,4,5-Trifluorophenylboronic Acid". Organic Syntheses . 79: 176; Collected Volumes, vol. 10, p. 80.
  4. ↑ Kidwell, R. L.; Murphy, M.; Darling, S. D. (1969). "Phenols: 6-Methoxy-2-naphthol". Organic Syntheses . 49: 90; Collected Volumes, vol. 10, p. 80.
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