Tetraethylammonium iodide explained

Tetraethylammonium iodide is a quaternary ammonium compound with the chemical formula C₈H₂₀N⁺I⁻. It has been used as the source of tetraethylammonium ions in pharmacological and physiological studies, but is also used in organic chemical synthesis.

Chemistry

Preparation

Tetraethylammonium iodide is commercially available, but can be prepared by the reaction between triethylamine and ethyl iodide.^[1]

Structure

The crystal structure of tetraethylammonium iodide has been determined.^[2] The crystal structure is a distorted wurtzite lattice. At the nitrogen atom, the coordination is a flattened tetrahedron. The N-C-C angle is slightly larger than the tetrahedral angle.

Synthetic applications

Examples include:

• Stereoselective formation of (Z)-diiodoalkenes by treatment of alkynes with ICl in the presence of tetraethylammonium iodide.^[3]
• 2-Hydroxyethylation (attachment of -CH₂-CH₂-OH) by ethylene carbonate of carboxylic acids and certain heterocycles bearing an acidic N-H. For example, benzoic acid is converted to the ester, 2-hydroxyethyl benzoate, by treatment with ethylene carbonate in the presence of tetraethylammonium iodide.^[4]
• Phase-transfer catalyst in geminal di-alkylation of fluorene, N,N-dialkylation of aniline and N-alkylation of carbazole using aqueous sodium hydroxide and alkyl halides.^[5]

Toxicity

LD₅₀: 35 mg/kg (mouse, i.p.); 56 mg/kg (mouse, i.v.)

See also

• Tetraethylammonium
• Tetraethylammonium bromide
• Tetraethylammonium chloride

Notes and References

1. A. A. Vernon and J. L. Sheard (1948). "The solubility of tetraethylammonium iodide in benzene-ethylene dichloride mixtures." J. Am. Chem. Soc. 70 2035-2036. https://doi.org/10.1021/ja01186a015
2. E. Wait and H. M. Powell (1958). "The crystal and molecular structure of tetraethylammonium iodide." J. Chem. Soc. 1872-1875.
3. N. Hénaff and A. Whiting (2000). "Stereoselective formation of 1,2-diiodoalkenes and their application in the stereoselective synthesis of highly functionalised alkenes via Suzuki and Stille coupling reactions." J. Chem. Soc., Perkin 1 395-400.
4. T.Yoshino et al. (1977). "Synthetic studies with carbonates. Part 6. Syntheses of 2-hydroxyethyl derivatives by reactions of ethylene carbonate with carboxylic acids or heterocycles in the presence of tetraethylammonium halides or under autocatalytic conditions." J. Chem. Soc., Perkin 1 1266-1272.
5. G. Saikia and P. K. Iyer (2010)."Facile C-H alkylation in water: enabling defect-free materials for optoelectronic devices." J. Org. Chem. 75 2714-2717.