Tetraethylammonium tetrafluoroborate

Description

Tetraethylammonium tetrafluoroborate is a quaternary ammonium salt consisting of a positively charged tetraethylammonium cation and a negatively charged tetrafluoroborate anion. This compound is commonly used as a phase transfer catalyst in organic chemical reactions, facilitating the transfer of reactants between immiscible phases. It can also be used as a reagent for synthesizing various organic compounds, an electrolyte in electrochemical experiments, and a source of tetraethylammonium ions in biochemical and pharmacological research.

Chemical Properties

white crystals or crystalline powder

Uses

Tetraethylammonium Tetrafluoroborate is used in the preparation of some organic salts of fluoboric acids.

General Description

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Synthesis

(1), boric acid refining:

Specific operations are as follows:

Industrial boric acid dissolved in boiling deionized water, and then filtered, the filtrate is reduced to room temperature, crystallization, filtration, and washed with deionized water, and then re-dissolve the cake in boiling deionized water, cooling, crystallization, and repeat the three times the recrystallization process, you can get the refining of boric acid, the yield of 42-50%;

(2) Fluoroboric acid preparation:

Weigh 100ml 40% (wt) hydrofluoric acid into the polytetrafluoro material with stirring, condensation reflux device and cooling coils in the reactor, while stirring in batches in 1 hour to add 34.5 grams of boric acid, the reaction temperature of 35 C, after adding boric acid continue to stir for half an hour, and then stop stirring and let it stand for 2 hours at room temperature, filtering! Remove the intolerable impurities, that is, 33% concentration of aqueous fluoboric acid solution;

(3) tetraethylammonium fluoroborate synthesis and refining:

Weigh 25g tetraethylammonium chloride and 50g butanol added to polytetrafluoro material in the reactor at 30 , 2 hours of slow droplets of aqueous fluoboric acid, and then warm to 40 to continue to react for 2 hours, the end of the reaction, reduced pressure Concentrate, and add 25g of butanol at room temperature, stirring for 2 hours for crystallization, filtration, and butanol wash to remove the mother liquor with impurities, the wet powder obtained - tetraethylammonium tetrafluoroborate 40g; tetraethylammonium tetrafluoroborate wet powder into a container with 150ml ethanol solution with a condensation reflux device, warming boiling After the solids were all dissolved, the temperature was lowered while stirring, cooled to room temperature, and crystallized, filtered, and washed with ethanol solution at room temperature, the recrystallization process was repeated twice, and after vacuum drying, 21g of qualified ammonium tetraethyl tetrafluoroborate product was obtained with a yield of 64.2% (mol).

Purification Methods

Dissolve the salt in hot MeOH, filter and add Et2O. It is soluble in ethylene chloride [Thompson & Kraus J Am Chem Soc 69 1016 1947, Wheeler & Sandstadt 77 2025 1955]. It has also been recrystallised three times from a mixture of ethyl acetate/hexane (5:1) or MeOH/pet ether, then stored at 95o for 48hours under vacuum [Henry & Faulkner J Am Chem Soc 107 3436 1985, Huang et al. Anal Chem 58 2889 1986]. It is used as a supporting electrolyte. [Beilstein 4 IV 333.]