Триметилборат химические свойства, назначение, производство
Химические свойства
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.
Использование
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, Trimethyl borate 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.
Подготовка
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
прикладной
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.
Определение
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.
Реакции
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
Общее описание
Trimethyl borate appears as a water-white liquid. Denser than water. Vapors heavier than air. Used as a solvent and fungicide for fruit.
Реакции воздуха и воды
Highly flammable. Rapidly decomposes in water.
Профиль реактивности
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.
Угроза здоровью
Trimethyl borate 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.
Пожароопасность
HIGHLY FLAMMABLE: Trimethyl borate 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.
Профиль безопасности
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.
Методы очистки
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.]
Триметилборат препаратная продукция и сырье
сырьё
препарат
Бензо [в] фуран-2-бороновой кислоты
Хинолин-8-бороновой кислоты
1-Methyl-4-pyrazole boronic acid pinacol ester
4-Isopropylbenzeneboronic кислота
2-(Methanesulfonylamino)phenylboronic acid
2-изопропенил-4,4,5,5-тетраметил-1,3,2-диоксаборолан
2- (N, N-ДИЭТИЛАМИНОКАРБОНИЛ) ФЕНИЛБОРОНОВАЯ КИСЛОТА
Бифенил-3-бороновой кислоты
2-FLUOROPHENYLBORONIC ACID
2-изопропоксифенилборная кислота
2-Naphthaleneboronic кислота
1-METHYL-1H-INDOLE-5-BORONIC ACID 2,2-DIMETHYL PROPANE DIOL-1,3-CYCLIC ESTER
Benzylboronic acid
4-трет-бутилфенилборная кислота
4- (метилтио) фенилбороновая кислота
2,3-диметилфенилборная кислота
2,6-дифторфенола
2,5-дихлорфенилборная кислота
1,4-Benzenediboronic кислота
3,5-диметилизоксазол-4-бороновой кислоты
2-фторфенилборная кислота
3,4-метилендиоксифенилборная кислота
5-METHOXYBENZOFURAN-2-BORONIC ACID
4-Benzyloxybenzeneboronic кислота
2-бензотиенилборная кислота
(4-PHENYLAMINOCARBONYLPHENYL)BORONIC ACID
Натрия тетрафенилбора
2,2'-BITHIOPHENE-5-BORONIC ACID
4-FLUORO-2-NITROPHENYLBORONIC ACID
2-Метоксипиридин-3-бороновой кислоты
2-Benzyloxyphenylboronic acid
4-цианофенилборная кислота
3-Methoxymethylphenylboronic acid
3,4,5-Трифторфенол
4-фтор-3-(гидроксиметил) бензолбороновой кислоты
Метил 4-боробензоат
4-феноксифенилборная кислота
5-индолилборная кислота
1-метил-1Н-пиразол-5-бороновой кислоты пинакон
Хинолин-5-бороновой кислоты