Tetramethylammonium bromide
[CAS# 64-20-0]

Identification

• Classification: Chemical reagent >> Organic reagent >> Amine salt (ammonium salt)
• Name: Tetramethylammonium bromide
• Molecular Formula: C₄H₁₂N.Br
• Molecular Weight: 154.05
• CAS Registry Number: 64-20-0
• EC Number: 200-581-2
• SMILES: C[N+](C)(C)C.[Br-]

Properties

• Density: 1.56 g/mL (Expl.)
• Melting point: 300 °C (Expl.)
• Water solubility: soluble

Safety Data

• Hazard Symbols: GHS06;GHS07 Danger
• Risk Statements: H300-H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P270-P271-P280-P301+P316-P302+P352-P304+P340-P305+P351+P338-P319-P321-P330-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	2	H300
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	3	H301
Specific target organ toxicity - single exposure	STOT SE	3	H336

• Transport Information: UN 2811

Discovery and Applications

Tetramethylammonium bromide (TMABr) is a quaternary ammonium salt with the chemical formula (CH3)4NBr. It consists of a tetramethylammonium cation, where four methyl groups are attached to a central nitrogen atom, paired with a bromide anion. TMABr is a white crystalline solid that is soluble in water and a variety of polar solvents such as alcohols and acetone. This compound is commonly used in both academic research and industrial applications due to its properties and reactivity.

Tetramethylammonium bromide was first synthesized in the early 20th century as part of the broader exploration of quaternary ammonium compounds. Quaternary ammonium salts have been of significant interest in the chemical and pharmaceutical industries due to their ability to interact with various organic and inorganic species. These compounds are well-known for their ability to serve as phase-transfer catalysts, surfactants, and reagents in organic synthesis.

One of the primary applications of tetramethylammonium bromide is in phase-transfer catalysis. In this process, TMABr facilitates the transfer of a reactant, usually an anion, between two immiscible phases, such as an organic solvent and an aqueous solution. This ability to mediate the movement of ions across phase boundaries improves the efficiency of a wide variety of chemical reactions, such as alkylation, nucleophilic substitution, and esterification. Phase-transfer catalysis is especially useful when reactants are poorly soluble in one of the phases, and the catalyst helps to bring the reactants together in the appropriate medium for reaction.

Tetramethylammonium bromide also serves as a precursor to other tetramethylammonium salts. For example, it can be converted to tetramethylammonium hydroxide by reacting it with a strong base. This hydroxide derivative has applications in the preparation of various organic and inorganic compounds, particularly in cases where a strong base is needed but the use of a more corrosive base (such as sodium hydroxide) is not desirable.

In addition to its use in phase-transfer catalysis and as a precursor, TMABr is utilized in several other chemical reactions. It has been employed in reactions involving alkylation and the synthesis of heterocyclic compounds. In some cases, TMABr has been shown to act as a nucleophilic source of methyl groups, which can be transferred to other substrates in reactions such as methylation.

The compound has also found use in electrochemistry and analytical chemistry. Tetramethylammonium bromide is sometimes used in the formation of ionic liquids, which are molten salts that remain in the liquid state at or near room temperature. These ionic liquids have applications as solvents and electrolytes in electrochemical processes, and TMABr can serve as a component in their synthesis.

Another significant application of tetramethylammonium bromide is in the field of biochemistry, where it is used in the preparation of certain reagents and buffers. For instance, TMABr has been used as a reagent in studies involving membrane transport and ion exchange, as it can help mimic certain aspects of ion transport in biological systems.

Tetramethylammonium bromide is generally considered to be of low toxicity, but like many chemicals, it should be handled with care. It can irritate the skin, eyes, and respiratory system, and appropriate safety precautions, such as wearing gloves, goggles, and working in a well-ventilated area, should be taken when handling the compound.

In summary, tetramethylammonium bromide is a versatile compound with a variety of applications in both academic and industrial settings. Its role as a phase-transfer catalyst, its ability to serve as a precursor to other tetramethylammonium salts, and its uses in alkylation, electrochemistry, and biochemistry make it an important reagent in organic synthesis and chemical research.

References

2024 Insight into the responses of the anammox granular sludge system to tetramethylammonium hydroxide (TMAH) during chip wastewater treatment Environmental Research
DOI: 10.1016/j.envres.2024.120099

2024 Re-evaluation of the reduced heart weights in male rats in a 28-day oral repeated-dose toxicity study of tetramethylammonium hydroxide Regulatory Toxicology and Pharmacology
DOI: 10.1016/j.yrtph.2024.105712

2024 Neurotoxicity of tetramethylammonium ion on larval and juvenile zebrafish: Effects on neurobehaviors and multiple biomarkers Journal of Environmental Sciences
DOI: 10.1016/j.jes.2023.09.005