Trimethyl borate

Summary

Trimethyl borate
Structural formula of trimethyl borate.svg
Trimethyl-borate-3D-vdW.png
Names
Preferred IUPAC name
Trimethyl borate
Other names
trimethoxyborane, boron trimethoxide
Identifiers
  • 121-43-7 checkY
3D model (JSmol)
  • Interactive image
ChEBI
  • CHEBI:38913 checkY
ChemSpider
  • 8157 checkY
ECHA InfoCard 100.004.063 Edit this at Wikidata
EC Number
  • 204-468-9
  • 8470
UNII
  • 82U64J6F5N checkY
  • DTXSID0037738 Edit this at Wikidata
  • InChI=1S/C3H9BO3/c1-5-4(6-2)7-3/h1-3H3 checkY
    Key: WRECIMRULFAWHA-UHFFFAOYSA-N checkY
  • 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
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
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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Infobox references

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]

Green fire of boric acid in methanol

Borate esters are prepared by heating boric acid or related boron oxides with alcohols under conditions where water is removed.[1]


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.[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. ^ a b c Robert J. Brotherton, C. Joseph Weber, Clarence R. Guibert, John L. Little (2000). "Boron Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH.CS1 maint: uses authors parameter (link)
  2. ^ 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
  3. ^ Kazuaki Ishihara, Suguru Ohara, Hisashi Yamamoto (2002). "3,4,5-Trifluorophenylboronic Acid". Organic Syntheses. 79: 176.CS1 maint: multiple names: authors list (link); Collective Volume, 10, p. 80
  4. ^ R. L. Kidwell, M. Murphy, and S. D. Darling (1969). "Phenols: 6-Methoxy-2-naphthol". Organic Syntheses. 49: 90.CS1 maint: multiple names: authors list (link); Collective Volume, 10, p. 80

External links

  • National Pollutant Inventory - Boron and compounds
  • MSDS for Trimethyl Borate
  • WebBook page for BC3H9O3