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Amines and amides

Tetramethylammonium hydroxide

Also known as TMAH, NMW-W, Hydroxyde de tetramethylammonium

CAS 75-59-2Formula C4H13NOMolar mass 91.15 g/molEC 200-882-9
GHS signal word: Danger. Pictograms: Corrosive, Acute toxicity (severe), Serious health hazard, Hazardous to the environment 44 suppliers listed
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Tetramethylammonium hydroxide chemical structure, C4H13NO, CAS 75-59-2
2D chemical structure

Key facts

What buyers check first

All properties
Appearance
The free base is known only in solution or as a solid pentahydrate, forming colorless, d…
Melting point
63 °C
Density
Specific gravity of solution approximately 1.00 at 24 °C/4 °C
HS code
292390
Category
Amines and amides
UN number
UN 3423
Illustrative photo, 200 litre steel drums of liquid in a chemical plant
Typical packagingIllustrative packaging image, not the actual product

What is Tetramethylammonium hydroxide?

Plain description, key identifiers and synonyms

Tetramethylammonium hydroxide is a solid in the hydrated form or a colorless liquid with a strong ammonia-like odor. It is soluble in water. It is corrosive to metals and tissue.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
tetramethylazanium hydroxide
CAS number
75-59-2 CAS number cross-checked
EC number
200-882-9
Molecular formula
C4H13NO
UNII
5GKP7317Q2
MDL number
MFCD00008280
InChIKey
WGTYBPLFGIVFAS-UHFFFAOYSA-M
InChI
InChI=1S/C4H12N.H2O/c1-5(2,3)4;/h1-4H3;1H2/q+1;/p-1
SMILES (canonical and isomeric)
C[N+](C)(C)C.[OH-]

Synonyms

  • TMAH
  • NMW-W
  • Hydroxyde de tetramethylammonium
  • Ammonium, tetramethyl-, hydroxide
  • NMD 3
  • Tetramethyl ammonium hydroxide
  • Methanaminium, N,N,N-trimethyl-, hydroxide
  • Methanaminium, N,N,N-trimethyl-, hydroxide (1:1)
  • TMAOH
  • tetramethylazanium, hydroxide
  • N,N,N-trimethylmethanaminium hydroxide
  • Tetramethylammoniumhydroxid
  • Tetrametanoamonio hydroxido
  • Tetrametiloamonio hydroxido
  • Tetramethylammonium hydroxide solution
  • Tetramethylammonium Hydroxide (25% w/w solution in Water)
  • tetramethylammoniumhydroxide
  • tetramethylammonium oxide
  • TMAH 10 % in water
  • tetramethylamonium hydroxide
  • N,N,N-Trimethylmethanaminium hydroxide (1:1)
  • tetramethylammonium, hydroxide
  • Tetramethylammonium hydroxide, 25% aq
  • Tetramethylammonium hydroxide 25 wt% in Methanol
  • Tetramethylammonium hydroxide, 10% aqueous solution
Show all 29 synonyms
  • Tetramethylammonium hydroxide, 25% aqueous solution
  • Tetramethylammonium hydroxide, 25% w/w in methanol
  • Tetramethylammonium hydroxide [UN1835] [Corrosive]
  • European Pharmacopoeia Reagent Tetramethylammonium Hydroxide Solution 1L

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

Appearance
The free base is known only in solution or as a solid pentahydrate, forming colorless, deliquescent needlesexp.
Odour
Strong ammonia-likeexp.
Melting point
63 °Cexp.
Density
Specific gravity of solution approximately 1.00 at 24 °C/4 °Cexp.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
91.15 g/molcalc.
Exact mass
91.0997 Dacalc.
LogP (octanol/water)
0.15calc.
Topological polar surface area
30 Ųcalc.
Hydrogen bond donors
0calc.
Hydrogen bond acceptors
1calc.
Rotatable bonds
0calc.
Heavy atoms
6calc.
Rings
0calc.
Aromatic rings
0calc.
Fraction sp3 carbons
1calc.
Formal charge
0calc.
Stereocentres
0calc.
Components
2calc.
Lipinski rule of five
Passes (0 violations)calc.

Calculated for screening. Confirm critical figures with the supplier.

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS05: Corrosive
Corrosive
GHS06: Acute toxicity (severe)
Acute toxicity (severe)
GHS08: Serious health hazard
Serious health hazard
GHS09: Hazardous to the environment
Hazardous to the environment

Hazard statements

  • H300 + H310Fatal if swallowed. Fatal in contact with skin.
  • H300Fatal if swallowed.
  • H310Fatal in contact with skin.
  • H311Toxic in contact with skin.
  • H314Causes severe skin burns and eye damage.
  • H318Causes serious eye damage.
  • H370Causes damage to organs.
  • H372Causes damage to organs through prolonged or repeated exposure.
  • H411Toxic to aquatic life with long lasting effects.
Precautionary statements (24)
  • P260Do not breathe dust, fume, gas, mist, vapours or spray.
  • P262Do not get in eyes, on skin, or on clothing.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P270Do not eat, drink or smoke when using this product.
  • P273Avoid release to the environment.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P301 + P316If swallowed: Get emergency medical help immediately.
  • P301 + P330 + P331If swallowed: Rinse mouth. Do not induce vomiting.
  • P302 + P352If on skin: Wash with plenty of water.
  • P302 + P361 + P354If on skin: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
  • P304 + P340If inhaled: Remove person to fresh air and keep comfortable for breathing.
  • P305 + P354 + P338If in eyes: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P308 + P316If exposed or concerned: Get emergency medical help immediately.
  • P316Get emergency medical help immediately.
  • P317Get medical help.
  • P319Get medical help if you feel unwell.
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P330Rinse mouth.
  • P361 + P364Take off immediately all contaminated clothing. And wash it before reuse.
  • P363Wash contaminated clothing before reuse.
  • P391Collect spillage.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.
UN number
UN 3423
Transport hazard class
8
Packing group
II

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Tetramethylammonium hydroxide suppliers

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All 44 suppliers
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Where suppliers are based

44 suppliers in 11 countries

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Tetramethylammonium hydroxide price

Indicative price range per kg from live supplier offers

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Uses and applications

What the substance is used for, by industry and function

Buffer, titrant, ion pair reagent, anisotropic etchant for silicon, in digestion of biological samples.

In electronics - surfactant/buffering agent in a developing solution for producing printed circuit boards ... surface active agent in formulation for polishing semiconductor wafers.

Chemical analysis basic medium.

In lithography for development.

Industrial uses: Laboratory chemicals, Chelating agent, Etching agent, Processing aids, specific to petroleum production, Intermediate, Ion exchange agent, Plating agent, Chemical reaction regulator.

Consumer uses: Adhesion/cohesion promoter, Etching agent.

Regulatory status

Inventories, regulations and trade controls that list this substance

United States

  • TSCA inventory (USA)
    Status: Active in US commerce

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Tetramethylammonium hydroxide is traded under.

HS 2923.90Indicative HS code

Quaternary ammonium salts and hydroxides whether or not chemically defined not elsewhere classified…

World exports in 2024
$1.07B
+14.4% vs 2023, imports $1.16B
2019 to 2024
Top exporters
  1. China36.7%
  2. United States14.2%
  3. Netherlands9.4%
Top importers
  1. South Korea10.7%
  2. Germany10.1%
  3. United States9.9%
Reported customs values in USD, not prices.Full trade data

The HS code shown for Tetramethylammonium hydroxide is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Tetramethylammonium hydroxide, based on the data on this page

What is Tetramethylammonium hydroxide?

Tetramethylammonium hydroxide is a solid in the hydrated form or a colorless liquid with a strong ammonia-like odor. It is soluble in water. It is corrosive to metals and tissue.

What is the CAS number of Tetramethylammonium hydroxide?

The CAS registry number of Tetramethylammonium hydroxide is 75-59-2.

What is the molecular formula and weight of Tetramethylammonium hydroxide?

The molecular formula of Tetramethylammonium hydroxide is C4H13NO and its molar mass is 91.15 g/mol.

What is Tetramethylammonium hydroxide used for?

Buffer, titrant, ion pair reagent, anisotropic etchant for silicon, in digestion of biological samples. In electronics - surfactant/buffering agent in a developing solution for producing printed circuit boards ... surface active agent in formulation for polishing semiconductor wafers. Chemical analysis basic medium.

Is Tetramethylammonium hydroxide hazardous?

Tetramethylammonium hydroxide carries the GHS signal word "Danger". Main hazards: fatal if swallowed. fatal in contact with skin, fatal if swallowed, fatal in contact with skin. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Tetramethylammonium hydroxide?

Tetramethylammonium hydroxide is usually classified under HS code 292390 (Quaternary ammonium salts and hydroxides, lecithins and other phosphoaminolipids…). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Tetramethylammonium hydroxide?

CompoundList lists 44 suppliers of Tetramethylammonium hydroxide in China, United States, India, Cyprus and 7 more. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

Where can I buy Tetramethylammonium hydroxide in India?

3 suppliers in India list Tetramethylammonium hydroxide on CompoundList. Filter the suppliers list by country and send a request to compare prices, grades and delivery times.

What is the price of Tetramethylammonium hydroxide?

Suppliers quote Tetramethylammonium hydroxide on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Tetramethylammonium hydroxide

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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