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Trimethylamine Basic information

Product Name:
  • Trimethylamine >=99.5%
  • Trimethylamine (ca. 13% in Acetonitrile, ca. 2mol/L)
  • Trimethylamine, 45% w/w aqueous solution
  • Trimethylamine water solution TMA Trimethylamine N,N-dimethyl-Methanamine
  • ai3-15639
  • dimethylmethaneamine
  • femanumber:3241
  • Methanamine, N,N-dimethyl-
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Mol File:

Trimethylamine Chemical Properties

Melting point:
283-284 °C (dec.)(lit.)
Boiling point:
3-4 °C(lit.)
0.83-0.88 g/mL at 20 °C
vapor density 
2.09 (vs air)
vapor pressure 
430 mm Hg ( 25 °C)
refractive index 
n20/D 1.357
Flash point:
38 °F
storage temp. 
very soluble in water, slightly soluble in alcohol, ether, benzene, toluene, xylene, ethylbenzene, chloroform maximum allowable concentration: TLV 10 p.p.m. (24 mg/m3) and STEL of 15 p.p.m. (36 mg/m3) (ACGIH 1986)
pKb (25°): 4.13
explosive limit
Water Solubility 
Soluble In Water, 8.9e+005 mg/L.
JECFA Number
Stable. Incompatible with a wide variety of materials, including bases, acids, oxidizing agents, brass, zinc, magnesium, aluminium, mercury, mercury oxides, acid chlorides, acid anhydrides. Hygroscopic. Highly flammable. Readily forms explosive mixtures with air.
CAS DataBase Reference
75-50-3(CAS DataBase Reference)

Safety Information

Hazard Codes 
Risk Statements 
Safety Statements 
UN 2924 3/PG 2
WGK Germany 
Autoignition Temperature
374 °F
HS Code 



Trimethylamine Usage And Synthesis

Chemical Properties

Colorless gas at room temperature; fishy ammoniacal odor; readily liquefied. Anhydrous form shipped as liquefied compressed gas. Soluble in water, alcohol, and ether.

Chemical Properties

Trimethylamine is compressed gas or liquid. Flammable gas. Shipped as a compressed gas, it may be present in an aqueous solution. It has a strong, fishy, ammoniacal odor. The Odor Threshold is 0.00011-0.87 ppm. Warning: The Odor Threshold range is so broad that odor alone should not be used as a warning of potentially hazardous exposures.

Chemical Properties

Trimethylamine has a pungent, fishy, ammoniacal odor at low concentration.


TMA is widely distributed in the environment as a normal constituent of animal and plant tissue and as a result of its formation during the decay of organic matter in plants, animals, fish, sewage and animal waste (Graedel 1978; Hippe et al 1977; Oremland et al 1982). The amine is formed primarily as the result of microbial degradation of the plant and animal constituents betaine and choline and from bacterial reduction of trimethylamine oxide, a common constituent of aquatic organisms. It also occurs naturally in a variety of foodstuffs and in tobacco smoke and these are the most likely sources of human exposure (HSDB 1988).
Numerous strains of bacteria isolated from various sources have been found capable of growing on TMA (HSDB 1988). Degradation products formed under anaerobic conditions include dimethylamine, formaldehyde, formate and C02, while under aerobic conditions, TMA is converted to dimethylamine, ammonia and methane.


Organic synthesis, especially of choline salts, warning agent for natural gas, manufacture of disinfectants, flotation agent, insect attractant, quaternary ammonium compounds, plastics.


From paraformaldehyde and ammonium chloride; by the action of formaldehyde and formic acid on ammonia.

Production Methods

Trimethylamine (TMA) is produced by several methods: from the reaction of ammonia and methanol; from paraformaldehyde and ammonium chloride; by the action of formaldehyde and formic acid on ammonia; and by the interaction of methanol and ammonia over a catalyst at high temperature (Hawley 1981; HSDB 1988). TMA is sold as an aqueous solution or as a liquefied gas (Windholz et al 1983) in which the aqueous solution is available as 25, 30, and 40% and anhydrous as 99% minimum. The impurities consist of ammonia at no more than 0.2% by weight of solution and formaldehyde at no more than 0.3% by wt. of solution (Rick 1985). U.S. production was estimated to be approximately 15,322 tons in 1984 (HSDB 1988).


ChEBI: A tertiary amine that is ammonia in which each hydrogen atom is substituted by an methyl group.

Aroma threshold values

Detection: 0.3 to 0.8 ppb; recognition: 500 ppb

General Description

A colorless gas with a fishlike odor at low concentrations changing to ammonia-like odor at higher concentrations. Shipped as a liquid under its own vapor pressure. Contact with the unconfined liquid can cause frostbite from evaporative cooling or chemical type burns. The gasis corrosive and dissolves in water to form flammable, corrosive solutions. Gas is an asphyxiate by the displacement of air. Produces toxic oxides of nitrogen during combustion. Prolonged exposure to heat can cause the containers to rupture violently and rocket. Long-term inhalation of low concentrations or short -term inhalation of high concentrations has adverse health effects.

Air & Water Reactions

Highly flammable and easily ignited. Water soluble.

Reactivity Profile

TRIMETHYLAMINE neutralizes acids in exothermic reactions to form salts plus water. May be incompatible with isocyanates, halogenated organics, peroxides, phenols (acidic), epoxides, anhydrides, and acid halides. Flammable gaseous hydrogen may be generated in combination with strong reducing agents, such as hydrides. Contamination of an ethylene oxide tank with trimethylamine caused an explosion [BCISC Quart. Safety Summ., 1966, 37, 44].

Health Hazard

VAPOR: POISONOUS IF INHALED. Irritating to eyes, nose, and throat. LIQUID: Will burn skin and eyes. Harmful if swallowed.

Health Hazard

Skin burns and eye irritation are produced upon contact with TMA (Beard and Noe 1981; Sittig 1985). Inhalation of vapors causes coughing and vomiting; higher concentrations produce difficult breathing and pulmonary edema. In one reported accident, the explosion of a glass ampule resulted in a blast of vapor striking the victim's eyes. Although no mechanical injuries were evident, the epithelium from the cornea was lost (Grant 1974). The epithelium healed promptly and the eye was entirely normal within 4-5 d.

Fire Hazard

FLAMMABLE. Flashback along vapor trail may occur. Vapor may explode if ignited in an enclosed area. Vapor is heavier than air and may travel a considerable distance to a source of ignition and flash back.

Industrial uses

TMA is used in the manufacturing of quaternary ammonium compounds, insect repellents, disinfectants, flotation agents, plastics, as a warning agent in gases, animal feed supplement, as a food additive for seafood flavor, and an ingredient in synthetic fermented egg protein product which is used to attract coyotes. In addition, it is used in organic synthesis of cationic emulsion polymers and as a chemical initiator for acetylcholine bromide [neuroregulator] (HSDB 1988; Anonymous 1981). The primary use (89%) is as a chemical intermediate for choline chloride (animal feed supplement), while 11% is used in other applications (HSDB 1988).

Safety Profile

Poison by intravenous route. Moderately toxic by subcutaneous and rectal routes. Mildly toxic by inhalation. A very dangerous fire hazard when exposed to heat or flame. Self-reactive. Moderately explosive in the form of vapor when exposed to heat or flame. Can react with oxidizing materials. To fight fire, stop flow of gas. Potentially explosive reaction with bromine + heat, ethylene oxide, triethynylaluminum. When heated to decomposition it emits toxic fumes of NOx. See also AMINES.

Potential Exposure

Trimethylamine is used as a chemical intermediate in organic synthesis of quaternary ammonium com pounds; as an insect attractant; as a warning agent in natural gas; flotation agent.


Aliphatic amines are well absorbed from the gut and respiratory tract (Beard and Noe 1981). However, TMA is a normal constituent of mammalian urine, complicating its pharmacokinetic analysis. TMA is partially metabolized to ammonia and subsequently to urea in mammals. It is converted in part to TMA oxide which is readily reduced back to TMA (Anon. 1972). TMA also is partially metabolized by N-demethylation to form formaldehyde (Parke 1968).
In an experiment using 4 male volunteers, over 95% of the administered TMA was excreted in the N-oxide form, confirming N-oxidation as the major route of metabolism in man (Al-Waiz et al 1987a). A condition known as trimethylaminuria (fish-odor syndrome) is likely to result from an inborn error in N-oxidation (Al-Waiz et al 1987b). Renal tubular transport and metabolism was investigated in chickens and TMA was found to be almost entirely metabolized in vivo to TMA oxide (Acara et al 1977).
In healthy humans, 2 mmol choline chloride, choline stearate, or lecithin administered orally markedly increased the urinary excretion of TMA, dimethylamine, and monomethylamine, with choline chloride having the greatest effect. Choline is known to be converted to TMA in mammals by gut microorganisms (HSDB 1988). When rats were treated with 1 mmol/kg of choline chloride or lecithin, urinary excretion of TMA was significantly increased while dimethylamine and monomethylamine excretion was not altered (Zeisel et al 1983).
TMA is reported to stimulate NADPH oxidation by an amount equivalent to the amount of TMA oxide formed (LaDu et al 1971).


UN1083 Trimethylamine, anhydrous, Hazard Class: 2.1; Labels: 2.1-Flammable gas. Cylinders must be transported in a secure upright position, in a wellventilated truck. Protect cylinder and labels from physical damage. The owner of the compressed gas cylinder is the only entity allowed by federal law (49CFR) to transport and refill them. It is a violation of transportation regulations to refill compressed gas cylinders without the express written permission of the owner. UN1297 Trimethylamine, aqueous solutions with not >50% trimethylamine by mass, Hazard Class: 3; Labels: 3-Flammable liquid, 8-Corrosive material.

Purification Methods

Dry triethylamine by passing the gas through a tower filled with solid KOH. Water and impurities containing labile hydrogen were removed by treatment with freshly sublimed, ground, P2O5. It has been refluxed with acetic anhydride, and then distilled through a tube packed with HgO and BaO. [Comyns J Chem Soc 1557 1955.] For more extensive purification, trimethylamine is converted to the hydrochloride, crystallised (see below), and regenerated by treating the hydrochloride with excess aqueous 50% KOH, the gas is passed through a CaSO4 column into a steel cylinder containing sodium ribbon. After 1-2 days, the cylinder is cooled to -78o and hydrogen and air are removed by pumping. [Day & Felsing J Am Chem Soc 72 1698 1950.] Me3N has been distlled from trap-to-trap and degassed by freeze-pump-thaw [Halpern et al. J Am Chem Soc 108 3907 1986]. It is commercially supplied in a pressure tin. [Beilstein 4 H 43, 4 I 322, 4 II 553, 4 III 99, 4 IV 134.]


A medium strong base. Violent reaction with strong oxidizers (such as chlorine, bromine, fluorine), ethylene oxide; nitrosating agents, for example, nitrites, sodium nitrite, nitrous gases, nitrous acid) capable of releasing carcinogenic nitrosamines.); keep away from mercury, strong acids. Corrosive to many metals, for example, zinc, brass, aluminum, copper, tin, and their alloys.

Waste Disposal

Return refillable compressed gas cylinders to supplier. Nonrefillable cylinders should be disposed of in accordance with local, state and federal regulations. Allow remaining gas to vent slowly into atmosphere in an unconfined area or exhaust hood. Refillabletype cylinders should be returned to original supplier with any valve caps and outlet plugs secured and valve protection caps in place.


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