Tetraethylammonium bromide (TEAB) is a

quaternary ammonium compound In organic chemistry, quaternary ammonium cations, also known as quats, are positively-charged polyatomic ions of the structure , where R is an alkyl group, an aryl group or organyl group. Unlike the ammonium, ammonium ion () and the primary, sec ...

with the chemical formula C₈H₂₀N⁺Br⁻, often written as "Et₄N⁺Br⁻" in the chemical literature. It has been used as the source of

tetraethylammonium Tetraethylammonium (TEA) is a quaternary ammonium cation with the chemical formula , consisting of four ethyl groups (, denoted Et) attached to a central nitrogen atom. It is a counterion used in the research laboratory to prepare lipophilic salt ...

ions in pharmacological and physiological studies, but is also used in organic chemical synthesis.

Chemistry

Synthesis

TEAB is commercially available, but can be prepared by the reaction between tetraethylammonium hydroxide and hydrobromic acid: :Et₄N⁺HO⁻ + HBr → Et₄N⁺Br⁻ + H₂O Evaporation of the water and recrystallization from acetonitrile yields a crystalline sample of TEAB.

Structure

The crystal structure of TEAB has been determined and found to exhibit a distorted tetrahedral symmetry with respect to the geometry of the C atoms around the central N.

Synthetic applications

Examples include: * TEAB catalyzes the high-yield oxidation of organic sulfides to

sulfoxides In organic chemistry, a sulfoxide, also called a sulphoxide, is an organosulfur compound containing a sulfinyl () functional group attached to two carbon atoms. It is a Chemical polarity, polar functional group. Sulfoxides are oxidized Derivativ ...

by o-iodoxybenzoic acid (IBX) in chloroform/water at room temperature, e.g. :(C₂H₅)₂S → (C₂H₅)₂S=O * TEAB has been used for the ''in situ'' preparation of tetraethylammonium superoxide from

potassium superoxide Potassium superoxide is an inorganic compound with the formula . It is a yellow paramagnetic solid that decomposes in moist air. It is a rare example of a stable salt of the superoxide anion. It is used as a scrubber, dehumidifier, and gene ...

for the conversion of primary

alkyl halides The haloalkanes (also known as halogenoalkanes or alkyl halides) are alkanes containing one or more halogen substituents of hydrogen atom. They are a subset of the general class of halocarbons, although the distinction is not often made. Haloalka ...

to dialkyl peroxides. The overall reaction is: :2R¹Br + 2KO₂ → R¹-O-O-R¹ + 2KBr + O₂

Biology

In common with

tetraethylammonium chloride Tetraethylammonium chloride (TEAC) is a quaternary ammonium compound with the chemical formula , sometimes written as . In appearance, it is a hygroscopic, colorless, crystalline solid. It has been used as the source of tetraethylammonium ions in ...

and tetraethylammonium iodide, TEAB has been used as a source of tetraethylammonium ions for numerous clinical and pharmacological studies, which are covered in more detail under the entry for

. Briefly, TEAB has been explored clinically for its ganglionic blocking properties, although it is now essentially obsolete as a drug, and it is still used in physiological research for its ability to block K⁺ channels in various tissues.

Toxicity

The toxicity of TEAB is primarily due to the tetraethylammonium ion, which has been studied extensively. The acute toxicity of TEAB is comparable to that of

and tetraethylammonium iodide. These data, taken from a study by Randall and co-workers,L. O. Randall, W. G. Peterson and G. Lehmann (1949). "The ganglionic blocking actions of thiophanium derivatives." ''J. Pharmacol. Exp. Ther.'' 97 48-57. are provided for comparative purposes; additional details may be found in the entry for

Tetraethylammonium Tetraethylammonium (TEA) is a quaternary ammonium cation with the chemical formula , consisting of four ethyl groups (, denoted Et) attached to a central nitrogen atom. It is a counterion used in the research laboratory to prepare lipophilic salt ...

. LD₅₀ for mouse: 38 mg/kg, i.v.; 60 mg/kg, i.p.; >2000 mg/kg, p.o.

References

Tetraethylammonium salts Bromides