Borate esters (original) (raw)
Borsäureester sind Ester der Borsäure, die zum Beispiel durch Reaktion von Borsäure mit Alkoholen unter Abspaltung von Wasser entstehen. Durch Destillation können die entstandenen Borsäureester gereinigt werden. Ein Beispiel dafür ist die Gewinnung von Borsäuretrimethylester (Trimethylborat), welcher manchmal synonym als Borsäureester bezeichnet wird, aus Borsäure und Methanol.
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| dbo:abstract | 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. A dehydrating agent, such as concentrated sulfuric acid is typically added. Borate esters are volatile and can be purified by distillation. This procedure is used for analysis of trace amounts of borate and for analysis of boron in steel. Like all boron compounds, alkyl borates burn with a characteristic green flame. This property is used to determine the presence of boron in qualitative analysis. Borate esters form spontaneously when treated with diols such as sugars and the reaction with mannitol forms the basis of a titrimetric analytical method for boric acid. Metaborate esters show considerable Lewis acidity and can initiate epoxide polymerization reactions. The Lewis acidity of orthoborate esters, as determined by the Gutmann-Beckett method, is relatively low. Trimethyl borate, B(OCH3)3, is used as a precursor to boronic esters for Suzuki couplings: Unsymmetrical borate esters are prepared from alkylation of trimethyl borate: These esters hydrolyze to boronic acids, which are used in Suzuki couplings. (en) Borsäureester sind Ester der Borsäure, die zum Beispiel durch Reaktion von Borsäure mit Alkoholen unter Abspaltung von Wasser entstehen. Durch Destillation können die entstandenen Borsäureester gereinigt werden. Ein Beispiel dafür ist die Gewinnung von Borsäuretrimethylester (Trimethylborat), welcher manchmal synonym als Borsäureester bezeichnet wird, aus Borsäure und Methanol. (de) Os ésteres de borato são compostos orgânicos preparados pela reação de condensação estequiométrica do ácido bórico com álcoois. Existem duas classes principais de ésteres de borato: ortoboratos, B(OR) 3 e metaboratos, B3O 3(OR) 3 . Metaboratos contêm anéis de boroxina de 6 membros. B (OH) 3 + 3 ROH → B (OR) 3 + 3 H2O3 B (OH) 3 + 3 ROH → B 3 O 3 (OR) 3 + 6 H 2 O Um agente desidratante, como ácido sulfúrico concentrado , é normalmente adicionado. Os ésteres de borato são voláteis e podem ser purificados por destilação. Este procedimento é utilizado, por exemplo, para análise de boro no aço. Como todos os compostos de boro, os boratos de alquila queimam com uma chama verde característica. Essa propriedade é usada para determinar a presença de boro na análise qualitativa. Os ésteres de metaborato mostram considerável acidez de Lewis e podem iniciar reações de polimerização de epóxido. A acidez de Lewis dos ésteres de ortoborato, determinada pelo método de Gutmann-Beckett, é relativamente baixa. O borato de trimetila, B (OCH3) 3, é utilizado como um precursor para ésteres borónicos para acoplamentos de Suzuki: ésteres de borato assimétricos são preparados a partir de alquilação de borato de trimetila: ArMgBr + B (OCH3) 3 → MgBrOCH 3 + ArB (OCH3)2ArB (OCH 3 ) 2 + 2H 2 O → ArB (OH) 2 + 2HOCH 3 Esses ésteres hidrolisam em ácidos borônicos, usados em acoplamentos Suzuki . (pt) Органические бораты (или борные эфиры) — борорганические соединения, сложные эфиры борной кислоты с общей формулой (RO)3B, где R — углеводородный радикал. (ru) |
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| rdfs:comment | Borsäureester sind Ester der Borsäure, die zum Beispiel durch Reaktion von Borsäure mit Alkoholen unter Abspaltung von Wasser entstehen. Durch Destillation können die entstandenen Borsäureester gereinigt werden. Ein Beispiel dafür ist die Gewinnung von Borsäuretrimethylester (Trimethylborat), welcher manchmal synonym als Borsäureester bezeichnet wird, aus Borsäure und Methanol. (de) Органические бораты (или борные эфиры) — борорганические соединения, сложные эфиры борной кислоты с общей формулой (RO)3B, где R — углеводородный радикал. (ru) 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. Borate esters form spontaneously when treated with diols such as sugars and the reaction with mannitol forms the basis of a titrimetric analytical method for boric acid. These esters hydrolyze to boronic acids, which are used in Suzuki couplings. (en) Os ésteres de borato são compostos orgânicos preparados pela reação de condensação estequiométrica do ácido bórico com álcoois. Existem duas classes principais de ésteres de borato: ortoboratos, B(OR) 3 e metaboratos, B3O 3(OR) 3 . Metaboratos contêm anéis de boroxina de 6 membros. B (OH) 3 + 3 ROH → B (OR) 3 + 3 H2O3 B (OH) 3 + 3 ROH → B 3 O 3 (OR) 3 + 6 H 2 O Os ésteres de metaborato mostram considerável acidez de Lewis e podem iniciar reações de polimerização de epóxido. A acidez de Lewis dos ésteres de ortoborato, determinada pelo método de Gutmann-Beckett, é relativamente baixa. (pt) |
| rdfs:label | Borate esters (en) Borsäureester (de) Éster de borato (pt) Органические бораты (ru) |
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