Triethylamine

Structural formula
General
Surname	Triethylamine
other names	N , N -diethylethanamine ( IUPAC ) TEA TRIETHYLAMINE ( INCI )
Molecular formula	C 6 H 15 N
Brief description	colorless to yellowish, oily liquid with an ammonia-like (when diluted, fish-like) odor
External identifiers / databases
CAS number 121-44-8 EC number 204-469-4 ECHA InfoCard 100.004.064 PubChem 8471 Wikidata Q139199
properties
Molar mass	101.19 g mol −1
Physical state	liquid
density	0.73 g cm −3
Melting point	−115.0 ° C
boiling point	89 ° C
Vapor pressure	69.6 h Pa (20 ° C) 112 hPa (30 ° C) 175 hPa (40 ° C) 263 hPa (50 ° C)
pK s value	10.76 (25 ° C)
solubility	good in water (80 g l −1 at 25 ° C)
Refractive index	1.4010
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 225-302-311 + 331-314-335 P: 210-280-303 + 361 + 353-304 + 340-310-305 + 351 + 338-403 + 233
MAK	DFG : 1 ml · m -3 or 4.2 mg · m -3 Switzerland: 1 ppm or 4.2 mg · m –3
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Triethylamine (TEA) is a basic solvent and a tertiary amine with the formula N (CH ₂ CH ₃ ) ₃ , whose molecular formula is often abbreviated as Et ₃ N. Compared to the simplest amine, ammonia , all three hydrogen atoms have been replaced by ethyl groups. This makes the molecule less volatile and much more lipophilic (non-polar). Like ammonia, it forms salt-like compounds with acids , which are called triethylammonium salts.

Extraction and presentation

The technical production of triethylamine takes place by reacting ethanol or bioethanol with ammonia at temperatures of 180-220 ° C and pressures of 20-70 bar in the presence of hydrogen over heterogeneous metal oxide catalysts which are applied to a porous carrier with little surface area.

The catalysts used are mixtures of metal oxides, which mainly consist of nickel (NiO), cobalt (CoO) and copper oxide (CuO) and are supported on aluminum oxide (Al ₂ O ₃ ) or zirconium dioxide (ZrO ₂ ). The reaction is preferably carried out in the gas phase and takes place continuously . The catalyst is arranged as a fixed bed in a tube or tube bundle reactor . The other ethylamines monoethylamine and diethylamine are also formed. However , their formation can be suppressed by an excess of ethanol . The product mixture is worked up and purified by distillation or rectification . Both the conversion and the selectivity are over 90% based on ethanol.

properties

Triethylamine is a colorless liquid that boils at 89 ° C under normal pressure . The vapor pressure function results according to Antoine according to log ₁₀ (P) = A− (B / (T + C)) (P in bar, T in K) with A = 2.98368, B = 695.814 and C = −128.271 in the temperature range from 323 to 367.8 K. The temperature dependence of the enthalpy of vaporization can be calculated according to the equation Δ _V H ⁰ = A · e ^{(−βT _r )} (1 − T _r ) ^β (Δ _V H ⁰ in kJ / mol, T _r = (T / T _c ) reduced temperature) with A = 50.32 kJ / mol, β = 0.2684 and T _c = 535.6 K in the temperature range between 298 K and 358 K.

Compilation of the most important thermodynamic properties

property	Type	Value [unit]	Remarks
Standard enthalpy of formation	Δ f H 0 liquid Δ f H 0 gas	−127.8 kJ mol −1 −92.9 kJ mol −1	as a liquid as a gas
Enthalpy of combustion	Δ c H 0 liquid	−4377.09 kJ mol −1
Heat capacity	c p	216.43 J mol −1 K −1 (25 ° C) 2.14 J g −1 K −1 (25 ° C).	as liquid as liquid
Critical temperature	T c	535.6 K
Enthalpy of evaporation	Δ V H	31.01 kJ mol −1	at normal pressure boiling point

At 1013 h Pa (normal pressure), triethylamine and water have a lower critical solution temperature, also known as the lower critical separation temperature, of 18.5 ° C. This means that below this temperature triethylamine can be mixed with water as desired and above this temperature it has a miscibility gap. The compound is miscible with ethanol, diethyl ether and most organic solvents.

Triethylamine reacts strongly exothermically with halogenated hydrocarbons , nitroalkanes , concentrated acids, nitrogen dioxide or oxidizing agents .

Triethylamine forms highly flammable vapor-air mixtures. The compound has a flash point of −7 ° C. The explosion range is between 1.2% by volume (50 g / m ³ ) as the lower explosion limit (LEL) and 8.0% by volume (340 g / m ³ ) as the upper explosion limit (UEL). The ignition temperature is 215 ° C. The substance therefore falls into temperature class T3.

use

In synthetic organic chemistry, triethylamine is used as a basic solvent. Furthermore, it is often used as an auxiliary base to bind acids released during reactions (see also: Diisopropylethylamine ). An example is the formation of esters from carboxylic acid chlorides and alcohols , in which hydrochloric acid is released. The acid is bound by the formation of triethylammonium salts, in the case of hydrochloric acid that is, triethylammonium chloride (see also: Hydrochloride ). It is also used as a catalyst in the production of various plastics and synthetic resins , such as polyurethanes and phenolic resins .

It can also be used as a component of rocket fuels (patent by BMW Flugmotorenbau from 1943, see Tonka ). It is also used as a raw material for the manufacture of pesticides , pharmaceuticals , paints and coating materials. As a fuel “tracer” in experimental transparent engines , it can be used for laser-induced fluorescence (LIF). In this case, a UV laser is used for excitation.

In foundry technology , triethylamine is used to achieve a chemical reaction and thus hardening of the sand-binder mixture (cold box process). Here, gaseous triethylamine is passed into the sand-binder mixture for 30 to 60 seconds. The casting mold is then cured at room temperature. Triethylamine can also be used to increase the pH value of triethylene glycol (TEG). TEG is used in dehydration.

Hazards and preventive measures

The substance causes severe burns of the respiratory tract when inhaling the vapors, sometimes with bloody sputum, as well as the skin, eyes and other mucous membranes on local contact. Auxiloson® spray ( dexamethasone ) can be administered in high doses as first aid for inhalative poisoning . In the event of skin contact, rinse off immediately with plenty of water and then dab off with polyethylene glycol (PEG) 400. Take off contaminated clothing immediately. Further treatment is left to the doctor to be called in immediately. If the eyes are affected, first rinse the affected eye with plenty of water (eye shower, etc.) for at least ten minutes and consult your ophthalmologist. If swallowed, vomiting should be avoided and the victim should drink plenty of fluids. A doctor must also be asked / consulted here. Systemic consequences of intoxication are known to be nausea, vomiting and headaches.

Triethylamine is highly flammable. The use of open flames in the workplace is prohibited. As a preventive measure, protective clothing, gloves and possibly respiratory protection should be worn when working with triethylamine. In case of danger, absorb with liquid-binding material (Rench Rapid, Chemizorb, Sand, Kieselguhr) and dispose of as hazardous waste. Use CO ₂ extinguishers, water or foam for small fires .

With long-term exposure, triethylamine shows mutagenic properties. A final decision has not yet been made on a classification as a carcinogen (status 2017).

Related links

• Ethylamine
• Diethylamine

Individual evidence

1. ↑ Entry on TRIETHYLAMINE in the CosIng database of the EU Commission, accessed on February 17, 2020.
2. ↑ ^{a b c d e f g h i j k l m n o} Entry on triethylamine in the GESTIS substance database of the IFA , accessed on December 22, 2017(JavaScript required) .
3. ↑ ^{a b c d e f g} Entry on triethylamine. In: Römpp Online . Georg Thieme Verlag, accessed on December 22, 2017.
4. ↑ Karsten Eller, Erhard Henkes, Roland Rossbacher, Hartmut Höke: Amines, Aliphatic . In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH Verlag, 2000, ISBN 3-527-30673-0 , doi : 10.1002 / 14356007.a02_001 .
5. ↑ Arthur I. Vogel: 365. Physical properties and chemical constitution. Part XIX. Five-membered and six-membered carbon rings . In: Journal of the Chemical Society (Resumed) . 1948, ISSN  0368-1769 , p. 1809 , doi : 10.1039 / JR9480001809 .
6. ↑ Entry on triethylamine in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
7. ↑ Schweizerische Unfallversicherungsanstalt (Suva): Limits - Current MAK and BAT values (search for 121-44-8 or triethylamine ), accessed on August 19, 2020.
8. ↑ ^{a b} Patent EP2782898B1 : Process for the production of ethylamines and mono-iso-propylamine (MIPA). Published on October 21, 2015 , applicant: BASF SE, inventors: Norbert Asprion, Manfred Julius, Oliver Bey, Stefanie Werland, Frank Stein, Matthias Kummer, Wolfgang Mägerlein, Johann-Peter Melder, Kevin Huyghe, Maarten Moors. ‌
9. ↑ HJ Bittrich, E. Kauer: On the thermodynamics of the system diethylamine-triethylamine. I. The liquid-vapor equilibrium. In: Z. Phys. Chem. (Frankfurt / Main) 219, 1962, pp. 224-238.
10. ^ ^{A b c} V. Majer, V. Svoboda: Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation. Blackwell Scientific Publications, Oxford 1985, p. 300.
11. ↑ ^{a b c} N. D. Lebedeva: Heats of combustion and formation of aliphatic tertiary amine homologues. In: Russ. J. Phys. Chem. (Engl. Transl.) 40, 1966, pp. 1465-1467.
12. ^ ^{A b} J. PE Grolier, G. Roux-Desgranges, M. Berkane, E. Jimenez, E. Wilhelm: Heat capacities and densities of mixtures of very polar substances 2. Mixtures containing N, N-dimethylformamide. In: J. Chem. Thermodyn. 25, 1993, pp. 41-50.
13. ↑ K. Stephan et al.: Thermodynamics: Fundamentals and technical applications. Volume II, Verlag Springer, ISBN 3-540-64481-4 , p. 94 ( limited preview in the Google book search).
14. ^ WJ Moore, DO Hummel: Physical chemistry. Verlag Walter de Gruyter, 1986, ISBN 3-11-010979-4 , p. 305 ( limited preview in the Google book search).
15. ↑ ^{a b c} E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft GmbH, Bremerhaven 2003.
16. ↑ e-EROS Encyclopedia of Reagents for Organic Synthesis , 1999-2013, John Wiley and Sons, entry for Triethylamine, accessed December 22, 2017.
17. ↑ Entry Triethylene Glycol at chemicalland21.com, accessed on December 9, 2015.