Preparation method of pinacolborane
A technology of pinacol borane and dichloroborane, which is applied in the field of preparation of pinacol borane, can solve the problems of high cost of borane and high market price of pinacol borane, and achieve simple synthesis method and cheap raw materials , The effect of easy access to raw materials
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[0025] The preparation method of pinacol borane provided by the present invention comprises the condensation reaction of pinacol and dichloroborane under alkaline conditions, and the specific reaction process is as follows:
[0026]
[0027] According to the preparation method of pinacol borane provided by the present invention, the basic conditions are usually controlled by adding an organic base to the reaction system.
[0028] The present invention does not specifically limit the amount of the dichloroborane, pinacol and organic base, as long as a condensation reaction product with pinacol borane as the main product can be obtained, preferably, the dichloroborane The molar ratio of alkane, pinacol and organic base is 1:1-1.5:2-4, more preferably 1:1-1.3:2-3, particularly preferably 1:1-1.2:2-2.5.
[0029] The organic base can be various existing basic organic compounds, specific examples of which include but are not limited to triethylamine, diisopropylethylamine, N,N-di...
Embodiment 1
[0040] This example is used to illustrate the preparation method of pinacol borane provided by the present invention.
[0041] Add 100 mL of dichloromethane to a 500 mL four-neck round-bottom flask under nitrogen protection, add 100 mL of dichloroborane solution (1.0 mol / L) in dioxane under cooling to 0 °C, and then add 11.82 g (0.1 mol) of dichloromethane. Nalcohol, add 20.24g (0.2mol) triethylamine dropwise, the pH value of the reaction system is 11 after dropping, then the temperature is raised to 20°C and the reaction is stirred for 12h, the solid is filtered off under nitrogen protection, and the filtrate is rectified under reduced pressure to obtain 11.25g pinacol borane, the yield is 88%, its 1 H NMR spectrum as figure 1 shown, from figure 1 It can be seen that the NMR signal at the chemical shift of 1.273 ppm is the four methyl signals of the product pinacol borane. It can be seen from this that the product prepared by the above method is indeed pinacol borane.
Embodiment 2
[0043] This example is used to illustrate the preparation method of pinacol borane provided by the present invention.
[0044]Add 100 mL of dichloromethane to a 500 mL four-neck round bottom flask under nitrogen protection, add 100 mL of dichloroborane in dioxane solution (1.0 mol / L) under cooling to 0 °C, and then add 15.37 g (0.13 mol) of dioxane solution. 38.77g (0.3mol) of diisopropylethylamine was added dropwise to aldol, the pH value of the reaction system was 11 after dropping, then the temperature was raised to 20°C and the reaction was stirred for 12h, the solid was filtered off under nitrogen protection, and the filtrate was decompressed. Rectification gave 11.45 g of pinacol borane with a yield of 89%.
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