Triethylamine is prepared by the alkylation of ammonia with ethanol: The pKa of protonated triethylamine is 10.75, and it can be used to prepare buffer solutions at that pH. The hydrochloride salt, triethylamine hydrochloride, is a colorless, odorless, and hygroscopic powder, which decomposes when heated to 261 °C. Triethylamine is soluble in water to the extent of 112.4 g/L at 20 °C. It is also miscible in common organic solvents, such as acetone, ethanol, and diethyl ether. Laboratory samples of triethylamine can be purified by distilling from calcium hydride. In alkane solvents triethylamine is a Lewis base that forms adducts with a variety of Lewis acid such as I2, phenols and Cu2. However when latter Lewis acid forms an adduct with triethylamine, steric repulsion between the ethyl groups and the Cu complex results. Triethylamine is classified as a soft base and its acceptor properties are discussed in the ECW model.
Applications
Triethylamine is commonly employed in organic synthesis as a base. For example, it is commonly used as a base during the preparation of esters and amides from acyl chlorides. Such reactions lead to the production of hydrogen chloride which combines with triethylamine to form the salt triethylamine hydrochloride, commonly called triethylammonium chloride. This reaction removes the hydrogen chloride from the reaction mixture, which can be required for these reactions to proceed to completion : Like other tertiary amines, it catalyzes the formation of urethane foams and epoxy resins. It is also useful in dehydrohalogenation reactions and Swern oxidations. Triethylamine is readily alkylated to give the corresponding quaternary ammonium salt: Triethylamine is mainly used in the production of quaternary ammonium compounds for textile auxiliaries and quaternary ammonium salts of dyes. It is also a catalyst and acid neutralizer for condensation reactions and is useful as an intermediate for manufacturing medicines, pesticides and other chemicals. Triethylamine salts like any other tertiary ammonium salts are used as an ion-interaction reagent in ion interaction chromatography, due to their amphiphilic properties. Unlike quaternary ammonium salts, tertiary ammonium salts are much more volatile, therefore mass spectrometry can be used while performing analysis. In alkane solvents triethylamine is a Lewis base that forms adducts with a variety of Lewis acid such as I2, phenols and Cu2. However when the latter Lewis acid forms an adduct with triethylamine, steric repulsion between the ethyl groups and the Cu complex results. Triethylamine is classified as a soft base and its acceptor properties are discussed in the ECW model.
Niche uses
Triethylamine is used to give salts of various carboxylic acid-containing pesticides, e.g. Triclopyr and 2,4-dichlorophenoxyacetic acid Triethylamine is the active ingredient in FlyNap, a product for anesthetizing Drosophila melanogaster. Triethylamine is used in mosquito and vector control labs to anesthetize mosquitoes. This is done to preserve any viral material that might be present during species identification. Also, the bicarbonate salt of triethylamine is useful in reverse phase chromatography, often in a gradient to purify nucleotides and other biomolecules. Triethylamine was found during the early 1940s to be hypergolic in combination with nitric acid, and was considered a possible propellant for early hypergolic rocket engines.
Natural occurrence
Hawthorn flowers have a heavy, complicated scent, the distinctive part of which is triethylamine, which is also one of the first chemicals produced by a dead human body when it begins to decay. For this reason, it is considered as unlucky to bring Hawthorn into the house. Gangrene is also said to possess a similar odour. On a brighter note, it is also described as 'the smell of sex', specifically of semen.
