Trimethylamine (TMA) is an organic compound with the formula N(CH3)3. It is a trimethylated derivative of ammonia. TMA is widely used in industry.[5][6] At higher concentrations it has an ammonia-like odor, and can cause necrosis of mucous membranes on contact.[7] At lower concentrations, it has a "fishy" odor, the odor associated with rotting fish.
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Names | |||
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Preferred IUPAC name
N,N-Dimethylmethanamine | |||
Other names
(Trimethyl)amine (The name trimethylamine is deprecated.)[2]
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Identifiers | |||
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3D model (JSmol)
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956566 | |||
ChEBI |
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ChEMBL |
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ChemSpider |
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ECHA InfoCard | 100.000.796 | ||
EC Number |
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KEGG |
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PubChem CID
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RTECS number |
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UNII |
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UN number | 1083 | ||
CompTox Dashboard (EPA)
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Properties | |||
C3H9N | |||
Molar mass | 59.112 g·mol−1 | ||
Appearance | Colorless gas | ||
Odor | Fishy, ammoniacal | ||
Density | 670 kg m−3 (at 0 °C) 627.0 kg m−3 (at 25 °C) | ||
Melting point | −117.20 °C; −178.96 °F; 155.95 K | ||
Boiling point | 3 to 7 °C; 37 to 44 °F; 276 to 280 K | ||
Miscible | |||
log P | 0.119 | ||
Vapor pressure | 188.7 kPa (at 20 °C)[3] | ||
Henry's law
constant (kH) |
95 μmol Pa−1 kg−1 | ||
Basicity (pKb) | 4.19 | ||
0.612 D | |||
Thermochemistry | |||
Std enthalpy of
formation (ΔfH⦵298) |
−24.5 to −23.0 kJ mol−1 | ||
Hazards | |||
GHS labelling: | |||
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Danger | |||
H220, H315, H318, H332, H335 | |||
P210, P261, P280, P305+P351+P338 | |||
NFPA 704 (fire diamond) | |||
Flash point | −7 °C (19 °F; 266 K) | ||
190 °C (374 °F; 463 K) | |||
Explosive limits | 2–11.6% | ||
Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
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500 mg kg−1 (oral, rat) | ||
NIOSH (US health exposure limits): | |||
PEL (Permissible)
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none[4] | ||
REL (Recommended)
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TWA 10 ppm (24 mg/m3) ST 15 ppm (36 mg/m3)[4] | ||
IDLH (Immediate danger)
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N.D.[4] | ||
Related compounds | |||
Related amines
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Related compounds
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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TMA is a colorless, hygroscopic, and flammable tertiary amine. It is a gas at room temperature but is usually sold as a 40% solution in water. It is also sold in pressurized gas cylinders.
TMA protonates to give the trimethylammonium cation. Trimethylamine is a good nucleophile, and this reactivity underpins most of its applications. Trimethylamine is a Lewis base that forms adducts with a variety of Lewis acids.[8]
Trimethylamine is prepared by the reaction of ammonia and methanol employing a catalyst:[5]
This reaction coproduces the other methylamines, dimethylamine (CH3)2NH and methylamine CH3NH2.
Trimethylammonium chloride has been prepared by a reaction of ammonium chloride and paraformaldehyde:[9]
Trimethylamine is produced by several routes in nature. Well studied are the degradation of choline and carnitine.[10]
Trimethylamine is used in the synthesis of choline, tetramethylammonium hydroxide, plant growth regulators, herbicides, strongly basic anion exchange resins, dye leveling agents and a number of basic dyes.[5][6] Gas sensors to test for fish freshness detect trimethylamine.
In humans, ingestion of certain plant and animal (e.g., red meat, egg yolk) food containing lecithin, choline, and L-carnitine provides certain gut microbiota with the substrate to synthesize TMA, which is then absorbed into the bloodstream.[11][12] High levels of trimethylamine in the body are associated with the development of trimethylaminuria, or fish odor syndrome, caused by a genetic defect in the enzyme which degrades TMA; or by taking large doses of supplements containing choline or L-carnitine.[11][12] TMA is metabolized by the liver to trimethylamine N-oxide (TMAO); TMAO is being investigated as a possible proatherogenic substance which may accelerate atherosclerosis in those eating foods with a high content of TMA precursors.[12] TMA also causes the odor of some human infections, bad breath, and bacterial vaginosis.
Trimethylamine is a full agonist of human TAAR5,[13][14][15] a trace amine-associated receptor that is expressed in the olfactory epithelium and functions as an olfactory receptor for tertiary amines.[15][16] One or more additional odorant receptors appear to be involved in trimethylamine olfaction in humans as well.[16]
Acute and chronic toxic effects of TMA were suggested in medical literature as early as the 19th century. TMA causes eye and skin irritation, and it is suggested to be a uremic toxin.[17] In patients, trimethylamine caused stomach ache, vomiting, diarrhoea, lacrimation, greying of the skin and agitation.[18] Apart from that, reproductive/developmental toxicity has been reported.[7] Some experimental studies suggested that TMA may be involved in etiology of cardiovascular diseases.[19][20]
Guidelines with exposure limit for workers are available e.g. the Recommendation from the Scientific Committee on Occupational Exposure Limits by the European Union Commission.[21]
Trimethylaminuria is an autosomal recessive genetic disorder involving a defect in the function or expression of flavin-containing monooxygenase 3 (FMO3) which results in poor trimethylamine metabolism. Individuals with trimethylaminuria develop a characteristic fish odor—the smell of trimethylamine—in their sweat, urine, and breath after the consumption of choline-rich foods. A condition similar to trimethylaminuria has also been observed in a certain breed of Rhode Island Red chicken that produces eggs with a fishy smell, especially after eating food containing a high proportion of rapeseed.[22][23]
The first dream of his own which Sigmund Freud tried to analyse in detail, when he was developing his theories about the interpretation of dreams, involved a patient of Freud's who had to have an injection of trimethylamine, and the chemical formula of the substance, written in bold letters on the bottle, jumping out at Freud.[24]
we review literature on trimethylamine (TMA), a microbiota-generated metabolite linked to atherosclerosis development.
Trimethylamine is exclusively a microbiota-derived product of nutrients (lecithin, choline, TMAO, L-carnitine) from normal diet, from which seems originate two diseases, trimethylaminuria (or Fish-Odor Syndrome) and cardiovascular disease through the proatherogenic property of its oxidized liver-derived form.
We show that [human TAAR5] responds to the tertiary amine N,N-dimethylethylamine and to a lesser extent to trimethylamine, a structurally related agonist for mouse and rat TAAR5 (Liberles and Buck, 2006; Staubert et al., 2010; Ferrero et al., 2012)