Tetraethylammonium chloride
Tetraethylammonium chloride 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 pharmacological and physiological studies, but is also used in organic chemical synthesis.
Preparation and structure
TEAC is produced by alkylation of triethylamine with ethyl chloride.TEAC exists as either of two stable hydrates, the monohydrate and tetrahydrate. The crystal structure of has been determined, as has that of the tetrahydrate,.
Details for the preparation of large, prismatic crystals of are given by Harmon and Gabriele, who carried out IR-spectroscopic studies on this and related compounds. These researchers have also pointed out that, although freshly-purified is free of triethylamine hydrochloride, small quantities of this compound form on heating of TEAC as the result of a Hofmann elimination:
Synthetic applications
To a large extent, the synthetic applications of TEAC resemble those of tetraethylammonium bromide and tetraethylammonium iodide, although one of the salts may be more efficacious than another in a particular reaction. For example, TEAC produces better yields than TEAB or TEAI as a co-catalyst in a reaction to prepare diarylureas from arylamines, nitroaromatics and carbon monoxide.In other examples, such as the following, TEAC is not as effective as TEAB or TEAI:
- 2-Hydroxyethylation by ethylene carbonate of carboxylic acids and certain heterocycles bearing an acidic N-H.
- 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.