Trialkylboranes

Trialkylboranes
General formula (R = alkyl)
Trimethylborane
Triethylborane

Trialkylboranes (BR ₃ ) are mostly unstable, air-sensitive compounds. They are therefore often processed further immediately after production.

Manufacturing

There are several methods for the synthesis of trialkylboranes:

• from hydrogen boride (BH ₃ ) and alkenes ,
• from boron trihalides - e.g. B. Boron trifluoride (BF ₃ ) - with Grignard compounds,
• from trialkyl derivatives of boroxine and
• from trialkylaluminum compounds.

The most atom-efficient method is the addition of hydrogen boride to the C = C double bond of alkenes. So BH ₃ reacts z. B. with ethene to triethylborane :

properties

In contrast to diborane (B ₂ H ₆ ), the trialkylboranes are in monomeric form because dimerization via two-electron three-center bonds is prevented for steric reasons.

use

The oxidation of the trialkylboranes with hydrogen peroxide (H ₂ O ₂ ) leads to alcohols. So z. B. Triethylborane oxidized to triethylborate and then hydrolyzed to ethanol under the action of sodium hydroxide solution :

Individual evidence

1. ↑ ^{a b c} Joachim Buddrus, Bernd Schmidt: Fundamentals of Organic Chemistry , 5th edition, de Gruyter Verlag, Berlin, 2015, pp. 176–178, ISBN 978-3-11-030559-3 .
2. ^ Siegfried Hauptmann : Organic Chemistry , 2nd revised edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, 1985, p. 237, ISBN 3-342-00280-8 .
3. ^ ^{A b} Siegfried Hauptmann: Organic Chemistry , 2nd revised edition, VEB Deutscher Verlag für Grundstoffindindustrie, Leipzig, 1985, p. 548, ISBN 3-342-00280-8 .
4. ↑ ^{a b} Otto Albrecht Neumüller (Editor): Römpp Chemie Lexikon , 8th edition, Frank'sche publishing firm, Stuttgart 1983, ISBN 3-440-04513-7 , S. 497th