Tetramethylammonium hydroxide Chemical Properties

Melting point:

°C

Boiling point:

110 °C

Density 

0.866 g/mL at 25 °C

vapor pressure 

17.5 mm Hg ( 20 °C)

refractive index 

n20/D 1.384

Flash point:

80 °F

storage temp. 

Store below +30°C.

solubility 

Methanol (Sparingly), Water (Slightly)

form 

Solution

color 

APHA: ≤10

PH

>13 (H2O, 20°C)

Odor

strong ammonia-like odor

Water Solubility 

Soluble in water.

Sensitive 

Air Sensitive

Merck 

14,9224

BRN 

3558708

Stability:

Stable. Flammable. Incompatible with strong oxidizing agents, strong acids.

InChIKey

WGTYBPLFGIVFAS-UHFFFAOYSA-M

CAS DataBase Reference

75-59-2(CAS DataBase Reference)

EPA Substance Registry System

Tetramethylammonium hydroxide (75-59-2)

Safety Information

Hazard Codes 

C,T,F,T+,Xn

Risk Statements 

24/25-34-20/21/22-39/23/24/25-23/24/25-10-21/22-25-21-11-67-36-52-48/24-27/28-23-35-36/38

Safety Statements 

45-36/37/39-26-16-36/37-28

RIDADR 

UN 3286 3/PG 2

WGK Germany 

1

RTECS 

PA0875000

F 

4.4-10-34

TSCA 

Yes

HazardClass 

3

PackingGroup 

II

HS Code 

29239000

Hazardous Substances Data

75-59-2(Hazardous Substances Data)

MSDS

• Language:English Provider:Tetramethylammonium hydroxide
• Language:English Provider:SigmaAldrich
• Language:English Provider:ACROS
• Language:English Provider:ALFA

Tetramethylammonium hydroxide Usage And Synthesis

Description

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

Chemical Properties

colourless to yellow liquid

Uses

Uses

Tetramethylammonium hydroxide is used to produce tetramethyl-ammonium azide. It is used as an anisotropic etchant of silicon, basic solvent in the development of acidic photoresist in photolithography process, as surfactant in the synthesis of ferrofluid and as a polarographic reagent. It finds application in the production of organic silicon, where it is used for computer silicon wafer surface brightener and cleaning agent. It is also involved in the purification of some metallic elements.
Tetramethylammonium hydroxide solution (25 wt.% solution in water) may be used as a base for pH adjustment to obtain hexagonal mesoporous aluminophosphate (TAP).

General Description

Tetramethylammonium hydroxide is a quaternary ammonium salt generally used as an anisotropic etchant for silicon due to its high silicon etching rate.

Reactivity Profile

Tetramethylammonium hydroxide acts like a base. Bases are chemically similar to sodium hydroxide (NaOH) or sodium oxide (Na2O). They neutralize acids exothermically to form salts plus water. When soluble in water they give solutions having a pH greater than 7.0. Mixing these materials with water can generate troublesome amounts of heat as the base is dissolved or diluted. Bases react with certain metals (such as aluminum and zinc) to form oxides or hydroxides of the metal and generate gaseous hydrogen. Bases may initiate polymerization reactions in polymerizable organic compounds, especially epoxides). They may generate flammable and/or toxic gases with ammonium salts, nitrides, halogenated organics, various metals, peroxides, and hydroperoxides. Materials of this group often serve as catalysts.

Health Hazard

TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.

Fire Hazard

Combustible material: may burn but does not ignite readily. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion hazards. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated. Runoff may pollute waterways. Substance may be transported in a molten form.

Safety Profile

Poison by subcutaneous route. A powerful caustic. A corrosive irritant to skin, eyes, and mucous membranes. When heated to decomposition it emits toxic fumes of NOx and NH3.

Purification Methods

It is freed from chloride ions by passage through an ion-exchange column (e.g. Amberlite IRA-400, prepared in its OH-form by passing 2M NaOH until the effluent is free from chloride ions, then washed with distilled H2O until neutral). A modification, to obtain carbonate-free hydroxide, uses the method of Davies and Nancollas [Nature 165 237 1950]. [Beilstein 4 IV 145.]

References

1.https://en.wikipedia.org/wiki/Tetramethylammonium_hydroxide#Uses
2.http://sacheminc.com/other-chemicals/tetramethylammonium-hydroxide-tmah/
3.https://www.fs.usda.gov/treesearch/pubs/15506
4.https://www.concordia.ca/content/dam/concordia/services/safety/docs/EHS-DOC-020_TMAHGuidelines.pdf
5./ChemicalProductProperty_EN_CB2854236.htm

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