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Skeletal formula of trimethylamine with all implicit hydrogens shown
Ball and stick model of trimethylamine
Spacefill model of trimethylamine
75-50-3 YesY
3DMet B00133
ChEBI CHEBI:18139 YesY
ChEMBL ChEMBL439723 YesY
ChemSpider 1114 YesY
EC number 200-875-0
Jmol-3D images Image
KEGG C00565 N
PubChem 1146
RTECS number PA0350000
UN number 1083
Molar mass 59.11 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
log P 0.119
Vapor pressure 188.7 kPa (at 20 °C) [2]
95 μmol Pa−1 kg−1
Basicity (pKb) 4.19
−24.5 to −23.0 kJ mol−1
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The corrosion pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
H220, H315, H318, H332, H335
P210, P261, P280, P305+351+338
EU classification Extremely Flammable F+ Harmful Xn
R-phrases R12, R20, R37/38, R41
S-phrases (S2), S16, S26, S29
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propane Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored 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):
500 mg kg−1 (oral, rat)
US health exposure limits (NIOSH):
TWA 10 ppm (24 mg/m3) ST 15 ppm (36 mg/m3)[3]
Related compounds
Related amines
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 N verify (what isYesY/N?)
Infobox references

Trimethylamine is an organic compound with the formula N(CH3)3. This colorless, hygroscopic, and flammable tertiary amine has a strong "fishy" odor in low concentrations and an ammonia-like odor at higher concentrations. It is a gas at room temperature but is usually sold in pressurized gas cylinders or as a 40% solution in water.

Trimethylamine is a product of decomposition of plants and animals. It is the substance mainly responsible for the odor often associated with rotting fish, some infections, bad breath and can be a cause of vaginal odor due to bacterial vaginosis. It is also associated with taking large doses of choline and carnitine.

Trimethylamine is a nitrogenous base and can be readily protonated to give 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.


Trimethylamine is prepared by the reaction of ammonia and methanol employing a catalyst:[4]

3 CH3OH + NH3 → (CH3)3N + 3 H2O

This reaction coproduces the other methylamines, dimethylamine (CH3)2NH and methylamine CH3NH2.

Trimethylamine has also been prepared via a reaction of ammonium chloride and paraformaldehyde,[5] according to the following equation:

9 (CH2=O)n + 2n NH4Cl → 2n (CH3)3N•HCl + 3n H2O + 3n CO2


Trimethylamine 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.[4][6] Gas sensors to test for fish freshness detect trimethylamine.


Main article: Trimethylaminuria

Trimethylaminuria is a genetic disorder in which the body is unable to metabolize trimethylamine from food sources. Patients develop a characteristic fish odour of their sweat, urine, and breath after the consumption of choline-rich foods. Trimethylaminuria is an autosomal recessive disorder involving a trimethylamine oxidase deficiency. 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.[citation needed]

See also[edit]


  1. ^ Merck Index, 11th Edition, 9625.
  2. ^ The Vapor Pressure of Trimethylamine from 0 to 40° (
  3. ^ a b c "NIOSH Pocket Guide to Chemical Hazards #0636". National Institute for Occupational Safety and Health (NIOSH). 
  4. ^ a b A. B. van Gysel, W. Musin "Methylamines" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. doi:10.1002/14356007.a16_535
  5. ^ Roger Adams, B. K. Brown. "Trimethylamine". Org. Synth. ; Coll. Vol. 1, p. 75 
  6. ^ Ashford's Dictionary of Industrial Chemicals (3rd ed.). 2011. p. 9362. ISBN 978-0-9522674-3-0. 

External links[edit]