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 and a metal alkoxide. 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

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<span class="mw-page-title-main">Imine</span> Organic compound or functional group containing a C=N bond

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<span class="mw-page-title-main">Sodium borohydride</span> Chemical compound

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<span class="mw-page-title-main">Triethyl orthoformate</span> Chemical compound

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<span class="mw-page-title-main">Tris(pentafluorophenyl)borane</span> Chemical compound

Tris(pentafluorophenyl)borane, sometimes referred to as "BCF", is the chemical compound (C6F5)3B. It is a white, volatile solid. The molecule consists of three pentafluorophenyl groups attached in a "paddle-wheel" manner to a central boron atom; the BC3 core is planar. It has been described as the “ideal Lewis acid” because of its high thermal stability and the relative inertness of the B-C bonds. Related fluoro-substituted boron compounds, such as those containing B−CF3 groups, decompose with formation of B-F bonds. Tris(pentafluorophenyl)borane is thermally stable at temperatures well over 200 °C, resistant to oxygen, and water-tolerant.

<span class="mw-page-title-main">Borohydride</span>

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<span class="mw-page-title-main">Lithium borohydride</span> Chemical compound

Lithium borohydride (LiBH4) is a borohydride and known in organic synthesis as a reducing agent for esters. Although less common than the related sodium borohydride, the lithium salt offers some advantages, being a stronger reducing agent and highly soluble in ethers, whilst remaining safer to handle than lithium aluminium hydride.

<span class="mw-page-title-main">Boronic acid</span> Organic compound of the form R–B(OH)2

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<span class="mw-page-title-main">Fluoroboric acid</span> Chemical compound

Fluoroboric acid or tetrafluoroboric acid is an inorganic compound with the simplified chemical formula H+[BF4]. Solvent-free tetrafluoroboric acid has not been reported. The term "fluoroboric acid" usually refers to a range of compounds including hydronium tetrafluoroborate, which are available as solutions. The ethyl ether solvate is also commercially available, where the fluoroboric acid can be represented by the formula [H( 2O)n]+[BF4], where n is 2.

<span class="mw-page-title-main">Phenylboronic acid</span> Chemical compound

Phenylboronic acid or benzeneboronic acid, abbreviated as PhB(OH)2 where Ph is the phenyl group C6H5-, is a boronic acid containing a phenyl substituent and two hydroxyl groups attached to boron. Phenylboronic acid is a white powder and is commonly used in organic synthesis. Boronic acids are mild Lewis acids which are generally stable and easy to handle, making them important to organic synthesis.

<span class="mw-page-title-main">Trimethyl phosphite</span> Chemical compound

Trimethyl phosphite is an organophosphorus compound with the formula P(OCH3)3, often abbreviated P(OMe)3. It is a colorless liquid with a highly pungent odor. It is the simplest phosphite ester and finds used as a ligand in organometallic chemistry and as a reagent in organic synthesis. The molecule features a pyramidal phosphorus(III) center bound to three methoxy groups.

<span class="mw-page-title-main">Sodium tetraphenylborate</span> Chemical compound

Sodium tetraphenylborate is the organic compound with the formula NaB(C6H5)4. It is a salt, wherein the anion consists of four phenyl rings bonded to boron. This white crystalline solid is used to prepare other tetraphenylborate salts, which are often highly soluble in organic solvents. The compound is used in inorganic and organometallic chemistry as a precipitating agent for potassium, ammonium, rubidium, and caesium ions, and some organic nitrogen compounds.

<span class="mw-page-title-main">Sodium metaborate</span> Chemical compound

Sodium metaborate is a chemical compound of sodium, boron, and oxygen with formula NaBO2. However, the metaborate ion is trimeric in the anhydrous solid, therefore a more correct formula is Na3B3O6 or (Na+)3[B3O6]3−. The formula can be written also as Na2O·B2O3 to highlight the relation to the main oxides of sodium and boron. The name is also applied to several hydrates whose formulas can be written NaBO2·nH2O for various values of n.

<span class="mw-page-title-main">Triphenylborane</span> Chemical compound

Triphenylborane, often abbreviated to BPh3 where Ph is the phenyl group C6H5-, is a chemical compound with the formula B(C6H5)3. It is a white crystalline solid and is both air and moisture sensitive, slowly forming benzene and triphenylboroxine. It is soluble in aromatic solvents.

<span class="mw-page-title-main">Borate esters</span> Organic compounds of the form B(OR)₃ or B₃O₃(OR)₃

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, B(OR)3 and metaborates, B3O3(OR)3. Metaborates contain 6-membered boroxine rings.

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   978-3527306732.
  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{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 10, p. 80.
  4. R. L. Kidwell, M. Murphy, and S. D. Darling (1969). "Phenols: 6-Methoxy-2-naphthol". Organic Syntheses . 49: 90{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 10, p. 80.