DE1162366B - Process for the preparation of boron trialkyls - Google Patents

Description

Process for the preparation of boron trialkyls The invention relates to refer to a process for the production of boron trialkyls by reacting boron hydrides with at least 2 boron atoms in the liquid phase.

Alkylboranes are of particular importance as intermediate products in the production of other chemical compounds, for example primary alcohols.

It is well known that alkylboranes are obtained by reacting an olefin, for example of pentene-1, with diborane in the presence of the dimethyl ether of diethylene glycol as a solvent. This method suffers from the important disadvantage that the application an inefficient solvent is required.

The present invention relates to a method of manufacture of boron trialkyls by reaction of borohydrides with at least 2 boron atoms in liquid phase, namely according to the invention, the reaction with a liquid Olefin with 6 to 20 carbon atoms without a catalyst at temperatures from -40 to 2000 C carried out.

The olefin that can be used as the solvent is that with the borohydride should be implemented.

In this case, preference is given to the presence of an excess of olefin taken care of in the reaction mixture, which also reduces the risk of explosion.

It is very desirable in practicing the invention Process between the borohydride and the olefin a good contact is established bring.

The suitable reaction temperatures are between -40 and 2000 C. Preferably the reaction temperature is room temperature. The pressure corresponds expediently that which arises automatically during the reaction, albeit a higher one Pressures can be applied.

Many olefins can be used in the process, but they must be liquid under the reaction conditions, such as the olefins with 6 to 20 carbon atoms. If the olefin does not contain a terminal double bond, so can a boron-carbon bond at an intermediate link in the carbon chain are formed. However, this boron-carbon intermediate member can operate at higher reaction temperatures isomerically rearranged into a link at the end of the carbon chain, whereby an alkylborane of type B (CH2R) is formed, in which R is an alkyl group. Alakylboranes of this type are of particular value as intermediates in manufacture primary alcohols. No protection is claimed here for isomerization.

The borohydride can be made from a diborane or other borohydrides such as Decaboran consist. The borohydride can in situ, for example, by reacting a Alkali metal borohydrides such as sodium borohydride can be prepared with an acid.

The procedure should be carried out in the absence of air and moisture will.

The invention is explained in more detail by means of the following examples.

Example 1 Diborane was in 86 g of pure 2-methylpentene-1, which at a temperature of 15 to 180 C was maintained, initiated. The excess olefin was then removed by distillation. 22.6 g of tri-2-methylpentylborane were obtained, Bp 8 126 to 1340 C. The boron content of the alkyl borane was 4.02% with a theoretical Value of 4.10 / 0. The yield was 850/0 of the theoretical calculated on the used diborane.

Example 2 Diborane was added to 70 g of 2-methylpentene-2 at 15-180 C initiated. After removing the excess olefin by distillation were 30 g of trihexylborane were obtained (boron content 4.47%, theoretical salary 4.1%). After distillation, tri- (2-methylpentyl) borane, boiling point 20 146 bis, was obtained 1640 c.

Example 3 Diborane was dissolved in 410 g of propylene trimer at 15 to 183 ° C initiated. After removing the excess olefin du crude distillation at reduced The residue was heated under pressure at 1600 ° C. for 4.5 hours and gave 370 g of trinonylborane (Boron content 3.2%, theoretical content 2.8%). The boron was attached to the primary carbon atoms bonded to the nonyl groups.

Example 4 Diborane was in 380 g of a heptene mixture at 15 to 180 C initiated. The heptene mixture was made by copolymerizing propylene made with butene. After removing the excess of heptenes by distillation a residue of 330 g of triheptylborane remained (boron content 3.6%, theoretical content 3.5%).

Example 5 Diborane was introduced into 90 g of Dissobutykn at 15 to 180.degree. The excess olefin was then distilled off and a residue of 35 g of trioctylborane obtained (boron content 3.50 / a, theoretical content 3.1%). The distillation of this The residue gave tris (2,4,4-trimethylpentyl) borane, Kpwlo 150 to 1620 C.

Example 6 5.7 g of sodium borohydride were mixed with 100 cc of 2-methylpentene-1 stirred, and 9 g of glacial acetic acid were added dropwise to the mixture at room temperature. The mixture was then refluxed for 2.5 hours, excess sodium borohydride decomposed by the addition of dilute hydrochloric acid and the product extracted with ether. The ether extract gave 1.5 g of trihexylborane (boron content 3.9%, theoretical content 4.19 / 0).

Claims (3)

Claims: 1. Process for the production of boron trialkyls by Implementation of borohydrides with at least 2 boron atoms in the liquid phase, since you r c h g e -k e n n n z e i c h n e t that the reaction with a liquid olefin with 6 to 20 carbon atoms carried out without a catalyst at temperatures from -40 to 2000 C. will. 2. The method according to claim 1, characterized in that the borohydride is produced in situ 3. The method according to claim 1 and 2, characterized in that that excess olefin is used as a solvent. Papers considered: Journal of the American Chemical Society, 70, pp. 2053-2055 (1948); Journal of ffie Chemical Society, 1950, pp. 2755 to 2759; Journal of Organic Chemistry, 22 (1957), pp. 1136, 1137. Older patents considered: German Patent No. 1 115736.