Tetraethylammonium bromide

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Tetraethylammonium bromide
Tetraethylammonium bromide.png
Identifiers
CAS number 71-91-0 YesY
PubChem 6285
ChemSpider 6048 YesY
ChEMBL CHEMBL324254
Jmol-3D images Image 1
Properties
Molecular formula C8H20NBr
Molar mass 210.16 g/mol
Appearance White solid
Density 1.4 g/cm3
Melting point 286 °C (dec)
Solubility in water Soluble
Hazards
MSDS External MSDS
R-phrases R36 R37 R38
S-phrases S26 S36
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Tetraethylammonium bromide (TEAB) is a quaternary ammonium compound with the chemical formula C8H20N+Br-, often written as "Et4N+Br-" in the chemical literature. It has been used as the source of tetraethylammonium ions in pharmacological and physiological studies, but is also used in organic chemical synthesis (see "Chemistry" section).

Chemistry[edit]

Synthesis[edit]

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.[1]

Structure[edit]

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.[2]

Synthetic Applications[edit]

Examples include:

(C2H5)2S → (C2H5)2S=O
2R1Br + 2KO2 → R1-O-O-R1 + 2KBr + O2

Biology[edit]

In common with tetraethylammonium chloride 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 Tetraethylammonium. Briefly, TEAB has been explored clinically for its ganglionic blocking properties,[5] 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.[6]

Toxicity[edit]

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 tetraethylammonium chloride and tetraethylammonium iodide. These data, taken from a study by Randall and co-workers,[7] are provided for comparative purposes; additional details may be found in the entry for Tetraethylammonium.

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

See also[edit]

References[edit]

  1. ^ D. N. Kevill and N. H. Cromwell (1961). "Elimination reactions of α-halogenated ketones. V. Kinetics of the bromide ion promoted elimination reaction of 2-benzyl-2-bromo-4,4-dimethyl-1-tetralone in solvent acetonitrile". J. Am. Chem. Soc. 83 3812-3815.
  2. ^ M. Ralle, J. C. Bryan, A. Habenschuss and B. Wunderlich (1997). "Low-temperature phase of tetraethylammonium bromide." Acta Cryst. Sect. C C53 488–490.
  3. ^ V. G. Shukla, P. D. Salgaonkar and K. G. Akamanchi (2003). "A mild, chemoselective oxidation of sulfides to sulfoxides using o-iodoxybenzoic acid and tetraethylammonium bromide as catalyst." J. Org. Chem. 68 5422-5425.
  4. ^ T. A. Foglia and L. S. Silbert (1992)."Preparation of di-n-alkyl peroxides: phase-transfer reaction of potassium superoxide with primary alkyl bromides." Synthesis 545-547.
  5. ^ A. M. Boyd et al. (1948). "Action of tetraethylammonium bromide." Lancet 251 15-18.
  6. ^ C. M. Armstrong and B. Hille (1972). "The inner quaternary ammonium receptor in potassium channels of the node of Ranvier." J. Gen. Physiol. 59 388-400.
  7. ^ L. O. Randall, W. G. Peterson and G. Lehmann (1949). "The ganglionic blocking actions of thiophanium derivatives." J. Pharmacol. Exp. Ther. 97 48-57.