Trimethylamine

Structural formula
General
Surname	Trimethylamine
other names	N , N -dimethylmethanamine TMA (not clear, see TMA ) NMe 3 Fagin
Molecular formula	C 3 H 9 N
Brief description	colorless gas that smells like fish or oil
External identifiers / databases
CAS number 75-50-3 EC number 200-875-0 ECHA InfoCard 100,000,796 PubChem 1146 Wikidata Q423953
properties
Molar mass	59.11 g mol −1
Physical state	gaseous
density	0.6535 g cm −3 (liquid at boiling point) 2.58 g l −1 (gas at 0 ° C and 1013 hPa) 2.5535 g l −1 (gas at 15 ° C and 1013 hPa)
Melting point	−117.1 ° C
boiling point	2.9 ° C
Vapor pressure	1.887 bar (20 ° C) 2.5 bar (30 ° C) 4.5 bar (50 ° C)
solubility	very easily soluble in water and ethanol
Dipole moment	0.612 (3) D (2.0 x 10 -30  C  ·  m )
Refractive index	1.3631 (0 ° C)
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 220-280-302 + 332-315-318-335 P: 210-261-280-305 + 351 + 338-410 + 403
MAK	DFG : 2 ml m −3 or 4.9 mg m −3 Switzerland: 2 ml m −3 or 4.9 mg m −3
Thermodynamic properties
ΔH f 0	−23.6 kJ / mol
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

Trimethylamine is a colorless, flammable gas with an intense, fish-like odor even when diluted; in higher concentrations it is more reminiscent of that of the chemically closely related ammonia . It is very hygroscopic , dissolves well in water and forms a very strong base in it . It comes on the market as a 40 percent aqueous solution, 33 percent solution in ethanol and as a liquefied gas.

Extraction and presentation

For the large-scale synthesis of trimethylamine, methanol is reacted with ammonia at temperatures of 350–450 ° C. and pressures of 15–25 bar in the presence of aluminum oxide ( silicate or phosphate ) in tubular reactors. In the first step, methanol reacts with ammonia to form methylamine. This then reacts with another equivalent of methanol to form dimethylamine. This secondary amine can then be methylated one final time to produce trimethylamine.

In addition to water , methylamine and dimethylamine are formed as by-products , which have to be separated off by multi-stage pressure and extractive distillation. Alternatively, these can be returned to the first reaction stage again in order to significantly increase the overall yield of trimethylamine. The weight ratio of mono-, di- and trimethylamine in this reaction is on average about 20:20:60.

The global production capacity for methylamines in 1996 was approximately 830,000 tons per year .

With more reactive methylating agents such as methyl iodide or dimethyl sulfate , ammonia can be methylated at low temperatures. However, this also gives mixtures of the possible methylation stages including the quaternary tetramethylammonium ion .

properties

Physical Properties

Trimethylamine is a colorless gas at room temperature. It can be liquefied by cooling it down or increasing the pressure. Trimethylamine is readily soluble in water and aliphatic alcohols such as. B. methanol. It has an unpleasant, fish-like or tran- to ammonia-like odor, which is noticeable at concentrations of 0.0005 to 4.2 mg / m³.

Chemical properties

Trimethylamine dissolves very easily in water, the solution reacts as a base. The molecule dissociates in aqueous solution according to:

${\displaystyle \mathrm {(CH_{3})_{3}N+H_{2}O\leftrightharpoons (CH_{3})_{3}NH^{+}+OH^{-}} }$

Trimethylamine, like all amines, is a weak base. With acids it forms ionically structured trimethyl ammonium salts, from which the trimethylamine can be released again with stronger bases.

The higher pK _s value of 9.81 - d. H. the stronger basicity - compared to ammonia (9.25) is explained by the + I effect of the three methyl groups . The still weaker basicity compared to the two amines with fewer methyl groups - methyl and dimethyl amine with pK _s 10.66 or 10.73 - can be derived from the steric hindrance of the free electron pair on the nitrogen atom of the alkalinity is responsible, explain .

Safety-related parameters

Trimethylamine forms highly flammable vapor-air mixtures. The compound has a flash point of −7 ° C. The explosion range is between 2.0% by volume (49 g / m ³ ) as the lower explosion limit (LEL) and 11.6% by volume (285 g / m ³ ) as the upper explosion limit (UEL). The limit gap width was determined to be 1.05 mm. This results in an assignment to explosion group IIA. The ignition temperature is 190 ° C. The substance therefore falls into temperature class T4.

use

The main by-product of trimethylamine is choline chloride , which can be produced by reacting ethylene oxide with an aqueous trimethylamine hydrochloride salt solution or by reacting trimethylamine with 2-chloroethanol (ethylene chlorohydrin). Trimethylamine is also used in the production of growth regulators , ion exchange resins and as a catalyst in organic synthesis .

Occurrence in nature

Trimethylamine can be detected in many organisms as a metabolite of the choline metabolism . Higher concentrations result from the microbial degradation of trimethylamine- N -oxide , which is abundant especially in sea fish, for example by bacteria of the genera Pseudomonas and Shewanella . An intense trimethylamine odor ("herring liquor") is therefore a sure sign of a lack of freshness. Trimethylamine continues to form in vaginal secretions and decomposed male ejaculate . Among the stand mushrooms , smut fungi such as stone brandy ( Tilletia caries ) are able to produce trimethylamine and to spoil the grains when attacked by wheat . Finally, some plants produce trimethylamine, such as stinking goosefoot ( Chenopodium vulvaria ) and forest ringwort ( Mercurialis perennis ). The amine is also found in the blossoms of the sweet chestnut , hawthorn , pear , mountain ash and other related rose plants and in barberries . In the latter case, it is believed to attract beetles as pollinator insects ( Cantharophilia ). Finally, beechnuts contain trimethylamine . Derived from the generic name of the common beech ( Fagus ), the substance is therefore also referred to as Fagin . The poisonous effect is reduced by roasting the fruit.

Trimethylamine is also produced in the human intestine, as a metabolic product after the ingestion of phosphatidylcholine , choline and carnitine , which are particularly found in eggs and meat . Trimethylamine is well absorbed and metabolized in the liver by flavin- containing monooxygenases (FMO3) to trimethylamine- N -oxide (TMAO). The enzyme FMO3 is a central regulator of the liver cholesterol metabolism and its elimination prevented the development of hyperglycaemia , hyperlipidaemia and atherosclerosis in insulin-resistant, overweight mice . The TMAO level is associated with an increased risk of cardiovascular diseases , particularly heart attacks and strokes , in humans . TMAO has pro- arteriosclerotic properties and increases the concentration of macrophage-specific cholesterol and the formation of foam cells in the vessel wall. In addition, TMAO increases platelet activity. When antibiotics were given , the TMAO blood level decreased. The formation of TMA can be inhibited by 3,3-dimethyl-1-butanol .

Effect on the human body

Trimethylamine is considered to be slightly toxic. It is irritating to the eyes and respiratory organs. A concentration that is hazardous to health can already be present when smell is perceived. If swallowed, the effects of vomiting with abdominal pain can lead to burns. Chemical burns can lead to the destruction of the skin, eyes, respiratory and digestive tract.

See also

• Trimethylaminuria ("fish odor" syndrome)

Web links

Commons : Trimethylamine  - Collection of pictures, videos, and audio files

Individual evidence

1. ↑ ^{a b c} Entry on trimethylamine. In: Römpp Online . Georg Thieme Verlag, accessed on May 13, 2014.
2. ↑ ^{a b c d e f g h i j k l m n o} Entry on trimethylamine in the GESTIS substance database of the IFA , accessed on August 31, 2017(JavaScript required) .
3. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Dipole Moments, pp. 9-58.
4. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-504.
5. ↑ Entry on Trimethylamine 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 .
6. ↑ Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 75-50-3 or trimethylamine ), accessed on September 17, 2019.
7. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-25.
8. ^ ^{A b} Marco Bosch, Roderich Röttger, Jan Eberhardt, Thomas Krug, Theodor Weber, Karl-Heinz Ross, Manfred Julius: Shaped bodies containing an aluminosilicate and aluminum oxide and a process for the continuous production of methylamines. In: Google Patents. BASF SE, November 14, 2012, accessed on May 2, 2019 . 
9. ↑ ^{a b} Hans-Jürgen Arpe: Industrial organic chemistry - important preliminary and intermediate products . 6th edition. WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 2007, ISBN 978-3-527-31540-6 , p. 55 .
10. ^ ^{A b c d} E. Brandes, W. Möller: Safety-related parameters - Volume 1: Flammable liquids and gases , Wirtschaftsverlag NW - Verlag für neue Wissenschaft GmbH, Bremerhaven 2003.
11. ^ Herbert Tilg: A Gut Feeling about Thrombosis . In: New England Journal of Medicine . tape 374 , no. 25 , 23 June 2016, p. 2494-2496 , doi : 10.1056 / NEJMcibr1604458 .