Tetramethylammonium chloride is one of the simplest

quaternary ammonium salts In chemistry, quaternary ammonium cations, also known as quats, are positively charged polyatomic ions of the structure , R being an alkyl group or an aryl group. Unlike the ammonium ion () and the primary, secondary, or tertiary ammonium cations ...

, with four methyl groups tetrahedrally attached to the central N. The chemical formula (CH₃)₄N⁺Cl⁻ is often abbreviated further as Me₄N⁺Cl⁻. It is a

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substan ...

colourless solid that is soluble in water and polar organic

solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

s. Tetramethylammonium chloride is a major industrial chemical, being used widely as a chemical reagent and also as a low-residue bactericide in such processes as hydrofracking. In the laboratory, it has fewer synthetic chemical applications than quaternary ammonium salts containing longer N-alkyl substituents, which are used extensively as phase-transfer catalysts.

Preparation and laboratory uses

Tetramethylammonium chloride is efficiently produced by the reaction of

trimethylamine 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 ...

and

methyl chloride Chloromethane, also called methyl chloride, Refrigerant-40, R-40 or HCC 40, is an organic compound with the chemical formula . One of the haloalkanes, it is a colorless, odorless, flammable gas. Methyl chloride is a crucial reagent in industria ...

. :N(CH₃)₃ + CH₃Cl → N(CH₃)₄⁺Cl⁻ It is produced by the

alkylation Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecti ...

of ammonium chloride with

dimethyl carbonate Dimethyl carbonate (DMC) is an organic compound with the formula OC(OCH3)2. It is a colourless, flammable liquid. It is classified as a carbonate ester. This compound has found use as a methylating agent and more recently as a solvent that is ...

in the presence of an

ionic liquid An ionic liquid (IL) is a salt in the liquid state. In some contexts, the term has been restricted to salts whose melting point is below a specific temperature, such as . While ordinary liquids such as water and gasoline are predominantly made of ...

catalyst. Except under extraordinary conditions, it is typically employed as a source of the inert counter cation Me₄N⁺. Similarly, it serves as a lipophilic precipitating agent. In low concentrations, it is used in

polymerase chain reaction The polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete or partial) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) ...

s to increase yields and specificity. It has been shown to enhance yields 5–10 fold at 60 mM by stabilizing the AT base pairs.

Toxicity

LD₅₀ = 25 mg/kg (mouse, i.p.); 40 mg/kg (mouse, s.c.); 50 mg/kg (rat, p.o.). Very toxic to aquatic organisms. Diverse data on human exposure, environmental toxicology and environmentally-related chemistry is available through the

NIH The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...

Toxnet database.

References

{{Reflist Tetramethylammonium salts

Preparation and laboratory uses

Toxicity

See also

References