Tetramethylammonium hydroxide
[CAS# 75-59-2]

Identification

• Classification: Pharmaceutical intermediate >> API intermediate
• Name: Tetramethylammonium hydroxide
• Synonyms: Tetramethyl ammonium hydroxide; Developer
• Molecular Formula: C₄H₁₃NO
• Molecular Weight: 91.15
• CAS Registry Number: 75-59-2
• EC Number: 200-882-9
• SMILES: C[N+](C)(C)C.[OH-]

Properties

• Density: 0.865 g/mL
• Melting point: 66-67 °C (Expl.)
• Refractive index: 1.384 (Expl.)
• Boiling point: 102 °C (Expl.)
• Flash point: 12 °C (Expl.)

Safety Data

• Hazard Symbols: GHS05;GHS06;GHS08;GHS09 Danger
• Risk Statements: H300+H310--H300-H310-H311-H314-H318-H370-H372-H411
• Safety Statements: P260-P262-P264-P264+P265-P270-P273-P280-P301+P316-P301+P330+P331-P302+P352-P302+P361+P354-P304+P340-P305+P354+P338-P308+P316-P316-P317-P319-P321-P330-P361+P364-P363-P391-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1B	H314
Acute toxicity	Acute Tox.	2	H300
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Acute toxicity	Acute Tox.	1	H310
Specific target organ toxicity - repeated exposure	STOT RE	1	H372
Specific target organ toxicity - single exposure	STOT SE	1	H370
Serious eye damage	Eye Dam.	1	H318
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	3	H301
Acute toxicity	Acute Tox.	2	H310
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Flammable liquids	Flam. Liq.	3	H226
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Flammable liquids	Flam. Liq.	1	H224
Skin corrosion	Skin Corr.	1A	H314
Skin corrosion	Skin Corr.	1	H314
Acute toxicity	Acute Tox.	4	H332
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413
Acute toxicity	Acute Tox.	3	H331
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin corrosion	Skin Corr.	1C	H314
Acute toxicity	Acute Tox.	4	H312

• Transport Information: UN 1835

Discovery and Applications

Tetramethylammonium hydroxide (TMAOH) is a quaternary ammonium hydroxide with the chemical formula (CH3)4NOH. It consists of a tetramethylammonium cation, where four methyl groups are attached to a central nitrogen atom, and a hydroxide anion. This compound is a strong base and is typically encountered in aqueous solution, where it dissociates into tetramethylammonium ions and hydroxide ions.

Tetramethylammonium hydroxide is often prepared by reacting tetramethylammonium salts, such as tetramethylammonium bromide or tetramethylammonium chloride, with a strong base like sodium hydroxide. The reaction produces TMAOH and the corresponding sodium salt. Tetramethylammonium hydroxide has been of particular interest in the fields of organic synthesis, electrochemistry, and material science due to its strong basic nature and its ability to act as a solvent or reagent in various chemical reactions.

One of the primary applications of tetramethylammonium hydroxide is in organic synthesis. It serves as a strong, non-corrosive base that is used in reactions such as deprotonation, alkylation, and nucleophilic substitution. Unlike other strong bases, such as sodium hydroxide or potassium hydroxide, TMAOH does not have the same tendency to form insoluble salts with organic acids, which can make it a more effective and selective reagent in certain reactions.

In particular, tetramethylammonium hydroxide is useful in the synthesis of a variety of organic compounds, including heterocycles and alkylated derivatives. It can also be employed in the preparation of ionic liquids, which are salts that remain liquid at or near room temperature. These ionic liquids have found diverse applications, including in electrochemistry and as solvents for chemical reactions.

Tetramethylammonium hydroxide is also used in the field of electrochemistry, where it can act as a component in the formation of ionic liquids or as an electrolyte in electrochemical processes. It has been incorporated into various electrochemical systems for energy storage and conversion, as well as in the development of new materials for batteries and capacitors.

In material science, TMAOH has been utilized in the preparation of thin films and coatings, particularly for use in semiconductor and nanotechnology applications. It can be employed as a precursor to materials that exhibit interesting electrical and optical properties, contributing to advancements in the development of new technologies.

Furthermore, tetramethylammonium hydroxide has applications in analytical chemistry, especially in techniques that involve ion exchange and membrane transport. Its strong basicity allows it to be used in certain types of chromatography and other separation techniques.

Despite its useful properties, tetramethylammonium hydroxide must be handled with caution. It is highly basic and can cause severe irritation to the skin, eyes, and respiratory system. Proper safety measures, including the use of personal protective equipment, should always be observed when working with this compound.

In conclusion, tetramethylammonium hydroxide is a versatile and important chemical in organic synthesis, electrochemistry, material science, and analytical chemistry. Its strong basicity, ability to form ionic liquids, and utility as a reagent in a variety of chemical reactions make it valuable in both academic research and industrial applications.

References

2024 Insight into the responses of the anammox granular sludge system to tetramethylammonium hydroxide (TMAH) during chip wastewater treatment. Environmental Research, 1, 120099.
DOI: 10.1016/j.envres.2024.120099

2024 A Modified Bosch Process of SF6/C4F8/O2 ICP-RIE Si Etching. Journal of Materials Engineering and Performance, 1, 10514.
DOI: 10.1007/s11665-024-10514-6

2024 CdS quantum dot aerogels for photocatalytic hydrogen evolution. Nano Research, 1, 7107.
DOI: 10.1007/s12274-024-7107-2