tetranbutylammonium

Tetrabutylammonium refers to the quaternary ammonium cation N,N,N,N-tetrabutylammonium, [N(C4H9)4]+. It forms salts with various counterions, such as chloride (tetrabutylammonium chloride, TBAC), bromide (tetrabutylammonium bromide, TBAB), tetrafluoroborate (TBABF4), hexafluorophosphate (TBAPF6), and related anions. The cation is bulky and highly lipophilic, which generally makes its salts soluble in organic solvents and only sparingly soluble in water, depending on the counterion.

Synthesis and preparation: Tetrabutylammonium salts are typically prepared by exhaustive alkylation of a tertiary amine, such as tri-n-butylamine, with an alkyl halide (for example, 1-bromobutane) to give tetrabutylammonium bromide, followed by metathesis to exchange the counterion if a different salt is desired.

Applications: The salts serve as phase-transfer catalysts in organic synthesis, helping transfer reactive anions across water–organic interfaces to enable a range of substitutions and condensations. They are also used as non-coordinating supporting electrolytes in nonaqueous electrochemistry, where their bulky cation minimizes strong ion pairing and supports electron-transfer studies in organic solvents.

Safety and handling: Tetrabutylammonium salts are generally handled as nonvolatile inorganic-type salts. They can be irritants and should be handled with appropriate precautions (gloves, eye protection, ventilation). They should be stored in a dry place to prevent hydrolysis or moisture uptake, depending on the counterion.

See also: Quaternary ammonium salt, Phase-transfer catalyst, Tetrabutylammonium chloride, Tetrabutylammonium hexafluorophosphate.