Trimethylamine

  • N, N- Dimethylmethanamin
  • TMA ( not unique, see TMA)
  • NMe3
  • Fagin

Colorless, obnoxious fish or tranartig smelling gas

Gaseous

  • 0.65 g · cm -3 ( liquid at boiling point)
  • 2.55 g · l-1 (gas at 15 ° C and 1000 hPa)

-117 ° C

2.9 ° C

1887 hPa (20 ° C)

Very slightly soluble in water and ethanol

0.612 (3 ) D ( 2.0 × 10-30 C · m)

1.3631 ( 0 ° C)

Risk

2 ppm -3, 4.9 mg / m³

-23.6 KJ / mol

Template: Infobox chemical / molecular formula search available

Trimethylamine is a colorless flammable gas with an intense even in high dilution fishy odor; at higher concentrations it reminds more to that of the chemically closely related ammonia. It is highly hygroscopic, readily soluble in water and forms is a fairly strong base. It comes as a 40 percent aqueous solution, 33 percent solution in ethanol and as a pressure-liquefied gas in the trade.

Production and representation

The large scale production of trimethylamine is effected by the reaction of methanol and ammonia bar at temperatures from 370 to 430 ° C and pressures of 20 to 30. The reaction is carried out in the gas phase on acidic heterogeneous catalysts based on silicon and aluminum oxides. Reaction products formed next to trimethylamine and water, methylamine CH3NH2 and dimethylamine ( CH3) 2NH:

The purification and workup of the reaction mixture is carried out by multi-stage distillation under pressure.

Reactive with methylating agents such as methyl iodide or dimethyl sulfate, ammonia can be methylated at low temperatures. However, one also obtains hereby mixtures of possible methylation levels including the quaternary Tetramethylammoniumions.

Properties

Physical Properties

At room temperature, trimethylamine is a colorless gas. It can be liquefied by cooling or pressure increase. Trimethylamine is readily soluble in water and aliphatic alcohols such as Methanol. It has an unpleasant, fish or tran - up ammonia -like odor, which already at concentrations of 0.0005 - / m³ is perceptible 4.2 mg.

Chemical Properties

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

The higher pKa value ( 9.81 ) compared to, for example, Ammonia ( 9.25 ) is due to the I effect of the three methyl groups. The still weaker basicity than the " intermediate links " methyl - and dimethylamine ( pK a 10.66 or 10.73 ) can be calculated from the steric hindrance of the free electron pair of the nitrogen atom, which is responsible for the basicity explain.

Trimethylamine, as any of the amines, is a weak base. With acids it forms ionic salts constructed from which it can be released with stronger bases again.

Use

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

Occurrence in nature

As a metabolite of choline metabolism can prove trimethylamine in many organisms. Higher concentrations produced during microbial degradation of trimethylamine N- oxide, which is abundant, especially in deep-sea fishing, for example by bacteria of the genera Pseudomonas and Shewanella. Intense trimethylamine odor ( " Herring Lake " ) is therefore a sure sign of lack of freshness. Trimethylamine continue in vaginal and decomposed male ejaculate. Among the stand mushrooms are smuts such as the bunt ( Tilletia caries ) is able to produce trimethylamine and to destroy the grains in case of infestation of wheat. Finally, some plants produce trimethylamine, for example, Stinking Goosefoot ( Chenopodium vulvaria ) and forest - Dog's Mercury ( Mercurialis perennis). Is also found in the flowers of chestnut, hawthorn, pear, mountain ash and other related rosaceous and barberries in the amine. In the latter it is probably the attraction of beetles as pollinators - insects ( Cantharophilie ). Finally, trimethylamine is included in beechnuts. Derived from the generic name of the beech ( Fagus ) the substance is therefore also known as Fagin. By roasting the fruit the poison effect is reduced.

Effect on the human body

Trimethylamine is considered slightly toxic. It is irritating to eyes and respiratory system. In olfaction may already be a harmful concentration. When swallowed, the effects of vomiting with abdominal pain can lead to burns. Burns can lead to destruction of skin, eyes, respiratory and digestive tract.

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