Synthesis of Tetrabutylammonium Bromide (TBAB)

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Tetrabutylammonium bromide is prepared buy mixing n-butylbromide with tributylamine in acetonitrile, in an inert atmosphere, under reflux conditions for a sufficient period of time to form a solution containing tetrabutylammonium bromide, cooling the resulting solution; mixing the solution with water, thus forming a mixture; and recovering tetrabutylammonium bromide in high yield from the mixture. (Must be done in acetonitrile or yeilds are very bad)

Method 1

A solution of 60.3 g. n-butylbromide and 74.1 g. tributylamine in 100 ml practical grade acetonitrile was refluxed for 22 hours under argon. The reaction mixture was cooled and then evaporated to near dryness at 30°C. The crystalline mass was dissolved in 100 ml water, and the aqueous solution was washed with three 100ml aliquots of benzene. Yield 90%.

Method 2

A solution of 60.3 g n-butylbromide and 64.14 g tributylamine (0.346 mole) in 200 ml chromatography quality acetonitrile was refluxed for 19 hours under an ethylene atmosphere. The reaction mixture was partially evaporated, then 600 ml diethylether was added to precipitate TBAB. The product was collected on a filter and dried in vacuo at ambient temperature. Yield 86%.

Reference: United States Patent 3,965,178