Tetramethylammonium chloride is one of the simplest
quaternary ammonium salts, with four
methyl groups tetrahedrally attached to the central N. The chemical formula (CH
3)
4N
+Cl
− is often abbreviated further as Me
4N
+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 substance ...
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
Fracking (also known as hydraulic fracturing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "frac ...
. 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.
:N(CH
3)
3 + CH
3Cl → N(CH
3)
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 effectin ...
of
ammonium chloride with
dimethyl carbonate 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 Me
4N
+. 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
A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both D ...
.
Toxicity
LD
50 = 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 1 ...
Toxnet database.
[
]
See also
* Quaternary ammonium cation
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 cat ...
* Tetraethylammonium chloride
Tetraethylammonium chloride (TEAC) is a quaternary ammonium compound with the chemical formula (C2H5)4N+Cl−, sometimes written as Et4N+Cl−. In appearance, it is a hygroscopic, colorless, crystalline solid. It has been used as the source of tet ...
* Tetramethylammonium hydroxide
Tetramethylammonium hydroxide (TMAH or TMAOH) is a quaternary ammonium salt with molecular formula N(CH3)4+ OH−. It is commonly encountered in form of concentrated solutions in water or methanol. TMAH in solid state and its aqueous solut ...
* Tetramethylammonium
Tetramethylammonium (TMA) or (Me4N+) is the simplest quaternary ammonium cation, consisting of four methyl groups attached to a central nitrogen atom, and is isoelectronic with neopentane. It is positively charged and can only be isolated in assoc ...
References
{{Reflist
Tetramethylammonium salts