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| | Trimethyl borate Basic information |
| | Trimethyl borate Chemical Properties |
| Melting point | -34 °C (lit.) | | Boiling point | 68-69 °C (lit.) | | density | 0.932 g/mL at 20 °C (lit.) | | vapor density | 3.59 (vs air) | | refractive index | n20/D 1.358(lit.) | | Fp | 8 °F | | storage temp. | Store at <= 20°C. | | solubility | Miscible with tetrahydrofuran, ether, isoporpylamine, hexane and methanol. | | form | Liquid | | Specific Gravity | 0.915 | | color | Colorless | | Water Solubility | reacts | | Sensitive | Moisture Sensitive | | Hydrolytic Sensitivity | 7: reacts slowly with moisture/water | | Merck | 14,9712 | | BRN | 1697939 | | Exposure limits | ACGIH: TWA 200 ppm; STEL 250 ppm (Skin)
OSHA: TWA 200 ppm(260 mg/m3)
NIOSH: IDLH 6000 ppm; TWA 200 ppm(260 mg/m3); STEL 250 ppm(325 mg/m3) | | Stability: | Stable. Incompatible with oxidizing agents. Decomposes slowly in the presence of moisture, rapidly in water. Flammable. | | InChIKey | WRECIMRULFAWHA-UHFFFAOYSA-N | | CAS DataBase Reference | 121-43-7(CAS DataBase Reference) | | NIST Chemistry Reference | Boric acid, trimethyl ester(121-43-7) | | EPA Substance Registry System | Boric acid (H3BO3), trimethyl ester (121-43-7) |
| | Trimethyl borate Usage And Synthesis |
| Chemical Properties | Water-white moisture-sensitive liquid, fumes in the air. It forms an azeotrope with methanol with an azeotrope of 55°C. Miscible with ether, methanol, hexane, tetrahydrofuran; It is stable in anhydrous state and decomposes into methanol and boric acid in presence of water. | | Uses | Trimethyl borate is a useful reagent in organic synthesis. It is involved in the production of resins, waxes and paints and acts as a methylation agent. As a boron source, it is used to prepare flame retardants, anti-oxidants and corrosion inhibitors. It reacts with Grignard reagents followed by hydrolysis to prepare boronic acid. It is also used as a precursor of borate esters, which finds application in the Suzuki coupling reaction. It is used as neutron detector gas in the presence of a scintillation counter; as a promoter of diborane reactions. | | Application | Trimethyl borate reacts with a Grignard reagent or organolithium compounds to yield dimethyl boronates, which upon subsequent aqueous acid treatment afford corresponding boronic acids. The resultant boronic acids or esters are useful intermediates in various cross-coupling reactions such as Suzuki coupling and Chan-Lam coupling. It is also used in the preparation of sodium borohydride. | | Definition | ChEBI: Trimethyl borate is a member of the class of borate esters obtained by the formal condensation of three equivalents of methanol with boric acid. | | Preparation | The preparation method of trimethyl borate
1. The direct reaction between boric acid and methanol is as follows:
3CH30H+H3B03→B (OCH3) 3+3H20
Usually the trimethyl borate formed in the reaction forms an azeotrope with excess methanol and is distilled out together, and then the trimethyl borate is obtained by separating the azeotrope.
2. The direct reaction between boron oxide and methanol is as follows:
B203+6CH30H→2B (OCH3) 3+3H20
3. Borax, methanol and sulfuric acid are directly reacted, and the reaction formula is :
Na2B4O7.1OH2O+12CH30H+2H2S04→4B (OCH3)3+2NaHS04+17H20 | | Reactions | Trimethyl borate B(OCH3)3 is a popular borate ester used in organic synthesis.
borate esters are prepared from alkylation of trimethyl borate:
ArMgBr + B(OCH3 )3 → MgBrOCH3 + ArB(OCH3 )2
ArB(OCH3 )2 + 2H2O → ArB(OH)2 + 2 HOCH3 | | General Description | Trimethyl borate appears as a water-white liquid. Denser than water. Vapors heavier than air. Used as a solvent and fungicide for fruit. | | Air & Water Reactions | Highly flammable. Rapidly decomposes in water. | | Reactivity Profile | Borates, such as Trimethyl borate, behave similarly to esters in that they react with acids to liberate heat along with alcohols and acids. Strong oxidizing acids may cause a vigorous reaction that is sufficiently exothermic to ignite the reaction products. Heat is also generated by the interaction of esters with caustic solutions. Flammable hydrogen is generated by mixing esters/borates with alkali metals and hydrides. | | Health Hazard | May cause toxic effects if inhaled or absorbed through skin. Inhalation or contact with material may irritate or burn skin and eyes. Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution. | | Fire Hazard | HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water. | | Safety Profile | Moderately toxic by
ingestion, skin contact, and intraperitoneal
routes. An eye irritant. A very dangerous fire
hazard when exposed to heat, flame, or
oxidizers. Moderately explosive when
exposed to flame. Will react with water or
steam to produce toxic and flammable
vapors. To fight fire, use dry chemical, CO2,
spray, foam. When heated to decomposition
it emits acrid smoke and irritating fumes.
See also ESTERS and BORON
COMPOUNDS. | | Purification Methods | Carefully fractionate the borate through a gauze-packed column. Re-distil and collect it in weighed glass vials and seal them. Keep it away from moisture. It undergoes alkyl exchange with alcohols and forms azeotropes, e.g. with MeOH the azeotrope consists of 70% (MeO)3B and 30% MeOH with b 52-54o/760mm, d 0.87. [Charnley et al. J Chem Soc 2288 1952, Gerrard & Lappert Chem Ind (London) 53 1952, Schlesinger et al. J Am Chem Soc 75 213 1953.] It has also been dried with Na and then distilled. [Beilstein 1 IV 1269.] |
| | Trimethyl borate Preparation Products And Raw materials |
| Raw materials | Tetramethyl orthosilicate | | Preparation Products | 2-ISOPROPOXYPHENYLBORONIC ACID-->3,4,5-Trifluorophenol-->1-Methyl-1H-pyrazole-5-boronic acid pinacol ester-->2-(Methanesulfonylamino)phenylboronic acid-->1-METHYL-1H-INDOLE-5-BORONIC ACID 2,2-DIMETHYL PROPANE DIOL-1,3-CYCLIC ESTER-->8-Quinolineboronic acid-->2,3-Dimethylphenylboronic acid-->4-FLUORO-2-NITROPHENYLBORONIC ACID-->1-Methyl-4-pyrazole boronic acid pinacol ester-->4-FLUORO-3-(HYDROXYMETHYL)BENZENEBORONIC ACID-->Sodium tetraphenylboron-->3,5-Dimethylisoxazole-4-boronic acid-->5-METHOXYBENZOFURAN-2-BORONIC ACID-->4-Benzyloxybenzeneboronic acid-->2-Benzyloxyphenylboronic acid-->4-(METHOXYCARBONYL)PHENYLBORONIC ACID-->2,2'-BITHIOPHENE-5-BORONIC ACID-->3-Methoxymethylphenylboronic acid-->4-Isopropylbenzeneboronic acid-->(4-PHENYLAMINOCARBONYLPHENYL)BORONIC ACID-->1,4-Phenylenebisboronic acid-->2,6-Difluorophenol-->4-Cyanophenylboronic acid-->2-Naphthaleneboronic acid-->5-Indolylboronic acid-->4-(Methylthio)phenylboronic acid-->Quinoline-5-boronic acid-->4-PHENOXYPHENYLBORONIC ACID-->2-Methoxypyridine-3-boronic acid-->Biphenyl-3-boronic acid-->Benzo[b]thien-2-ylboronic acid-->2,5-Dichlorophenylboronic acid-->2-(N,N-DIETHYLAMINOCARBONYL)PHENYLBORONIC ACID-->3,4-METHYLENEDIOXYPHENYLBORONIC ACID-->Isopropenylboronic acid pinacol ester-->4-tert-Butylphenylboronic acid-->Benzofuran-2-boronic acid-->2-Fluorophenylboronic acid-->2-FLUOROPHENYLBORONIC ACID-->Benzylboronic acid |
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