Trimethylamine (TMA) is an organic compound with the formula N(CH3)3. It 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 is a nitrogenous base and can be readily protonated to give the trimethylammonium cation. Trimethylammonium chloride is a hygroscopic colorless solid prepared from hydrochloric acid. Trimethylamine is a good nucleophile, and this reaction is the basis of most of its applications. TMA is widely used in industry: it is used in the synthesis of choline, tetramethylammonium hydroxide, plant growth regulators or herbicides, strongly basic anion exchange resins, dye leveling agents, and a number of basic dyes. At higher concentrations it has an ammonia-like odor, and can cause necrosis of mucous membranes on contact. At lower concentrations, it has a "fishy" odor, the odor associated with rotting fish.
|Preferred IUPAC name
(Trimethyl)amine (The name trimethylamine is deprecated.)
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||59.112 g·mol−1|
|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|
|Vapor pressure||188.7 kPa (at 20 °C)|
|95 μmol Pa−1 kg−1|
Std enthalpy of
|−24.5 to −23.0 kJ mol−1|
|GHS Signal word||Danger|
|H220, H315, H318, H332, H335|
|P210, P261, P280, P305+351+338|
|NFPA 704 (fire diamond)|
|Flash point||−7 °C (19 °F; 266 K)|
|190 °C (374 °F; 463 K)|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|500 mg kg−1 (oral, rat)|
|NIOSH (US health exposure limits):|
|TWA 10 ppm (24 mg/m3) ST 15 ppm (36 mg/m3)|
IDLH (Immediate danger)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
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. 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. 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. TMA also causes the odor of some human infections, bad breath, and bacterial vaginosis.
Trimethylamine is a full agonist of human TAAR5, a trace amine-associated receptor that is expressed in the olfactory epithelium and functions as an olfactory receptor for tertiary amines. One or more additional odorant receptors appear to be involved in trimethylamine olfaction in humans as well.
- 3 CH3OH + NH3 → (CH3)3N + 3 H2O
- 9 (CH2=O)n + 2n NH4Cl → 2n (CH3)3N•HCl + 3n H2O + 3n CO2↑
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. In patients, trimethylamine caused stomach ache, vomiting, diarrhoea, lacrimation, greying of the skin and agitation. Apart from that, reproductive/developmental toxicity has been reported.
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.
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. Gas sensors to test for fish freshness detect trimethylamine.
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.
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we review literature on trimethylamine (TMA), a microbiota-generated metabolite linked to atherosclerosis development.
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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.
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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).
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Table 2: Microbial metabolites: their synthesis, mechanisms of action, and effects on health and disease
Figure 1: Molecular mechanisms of action of indole and its metabolites on host physiology and disease
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- Molecule of the Month: Trimethylamine
- NIST Webbook data
- CDC - NIOSH Pocket Guide to Chemical Hazards
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