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Concept
Triméthylamine
Résumé
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: 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.
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 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. Trimethylamine is a Lewis base that forms adducts with a variety of Lewis acids.
Trimethylamine is prepared by the reaction of ammonia and methanol employing a catalyst:
3 CH3OH + NH3 → (CH3)3N + 3 H2O
This reaction coproduces the other methylamines, dimethylamine (CH3)2NH and methylamine CH3NH2.
Trimethylamine has also been prepared by a reaction of ammonium chloride and paraformaldehyde:
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, herbicides, strongly basic anion exchange resins, dye leveling agents and a number of basic dyes. Gas sensors to test for fish freshness detect trimethylamine.
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.
Source officielle
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