Boron trifluoride diglymate

A 500-ml flask is equipped with a thermometer, a magnetic stirrer, and a dropping funnel, and all openings are protected by drying tubes. The system is flushed with nitrogen and a solution of 2.84 g (0.075 mole) of sodium borohydride in 150 ml of diglyme is introduced followed by 28.3 g (0.30 mole) of norbornene. The flask is immersed in an ice-water bath and the hydroboration is achieved by the dropwise addition of 27.4 ml (0.10 mole) of boron trifluoride diglymate. The solution is stirred... 

Boron trifluoride diglymate is prepared (2) by mixing one part (by volume) of distilled boron trifluoride etherate with two parts (by volume) of diglyme. The ether is pumped otf under vacuum... 

The sodium borohydride solution is added dropwise to the stirred boron trifluoride etherate-diglyme solution resulting in the formation of diborane. The gas is swept into the olefin-TH F solution (held at 20°) by maintaining a slow flow of dry nitrogen through the generator. 

A 500-ml three-necked flask is fitted with a condenser, a pressure-equalizing dropping funnel, a magnetic stirrer, and a thermometer. The flask is charged with a mixture of 33.6 g (0.48 mole) of 2-methyl-2-butene and 180 ml of a 1 M solution of sodium boro-hydride in diglyme. The flask is cooled in an ice bath and stirring begun. Boron trifluoride etherate (0.24 mole) is added dropwise to the mixture and the solution is stirred at 0° for 2 hours. 

I. Diglyme, bis(2-methoxyethyI) ether EK, A Boron trifluoride etherate EK, MCB... 

Reduction of aromatic carboxylic acids to alcohols can be achieved by hydrides and complex hydrides, e.g. lithium aluminum hydride 968], sodium aluminum hydride [55] and sodium bis 2-methoxyethoxy)aluminum hydride [544, 969, 970], and with borane (diborane) [976] prepared from sodium borohydride and boron trifluoride etherate [971, 977] or aluminum chloride [755, 975] in diglyme. Sodium borohydride alone does not reduce free carboxylic acids. Anthranilic acid was reduced to the corresponding alcohol by electroreduction in sulfuric acid at 20-30° in 69-78% yield [979],... 

Borane generated from sodium borohydride and boron trifluoride etherate in diglyme reduced 7V-arylsubstituted succinimides to JV-arylpyrrolidones in 42-72% yields [7726]. 

Diborane is prepared by the reaction of sodium borohydride with iodine or boron trifluoride or trichloride in diglyme ... 

This borane reagent may be prepared as follows.6 In a dry 500-ml flask equipped with a condenser, a thermometer and a pressure-equalising dropping funnel are placed 80 ml of diglyme, 23.1 g of 2-methylbut-2-ene (0.33 mol) in 20ml of diglyme and 4.7 g of sodium borohydride (0.125 mol). The flask is immersed in an ice bath and 23.5 g of boron trifluoride-etherate (0.165 mol) is added dropwise over a period of 30 minutes. The semi-solid reaction mixture containing 0.165 mol of disiamylborane is permitted to remain an additional 15 hours at 0-5 °C, and then used for hydroboration. Examples of the use of disiamylborane are described in Sections 5.4.3 p. 542 and 5.7.1, p. 588. 

Reaction with trialkylboranes. Trialkylboranes when treated with silver nitrate in the presence of either sodium hydroxide or potassium hydroxide undergo coupling.20 For example, 1-hexene is hydroborated with sodium borohydride and boron trifluoride in diglyme. Aqueous potassium hydroxide is then added followed by aqueous silver nitrate. The major product is n-dodecane (66%). Other products are 5-methylundecanc (5%) and a mixture of 1-hexene and n-hexane. Yields of coupled products are somewhat lower in the case of internal olefins. Coupling of mixed trialkylboranes is also possible.21... 

Diborane. B2H6 is of special interest because it is the starting material for preparation of various other boron hydrides and because of its synthetic uses. It can be prepared in essentially quantitative yield by reaction of metal hydrides with boron trifluoride, a convenient method being to drop boron trifluoride etherate into a solution of sodium borohydride in diglyme (diethylene glycol dimethyl ether) ... 

Although several other methods for preparing the simplest borane are known (132), this method represents a convenient laboratory route to the hydride. However, when sodium borohydride is used, the above equation does not completely represent the course of reaction unless sodium borohydride is added in increments to boron trifluoride, both reagents being dissolved in diglyme.10 If a deficiency of boron trifluoride is added to sodium borohydride dissolved in diglyme, the reaction,... 

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