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Tetramethylammonium hydroxide solution

25 wt. % in H2O

TMAH solution
Linear Formula:
CAS Number:
Molecular Weight:
MDL number:
PubChem Substance ID:

Quality Level

vapor pressure

17.5 mmHg ( 20 °C)


25 wt. % in H2O

refractive index

n20/D 1.3806


1.016 g/mL at 25 °C

SMILES string




InChI key


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Tetramethylammonium hydroxide solution (25 wt.% solution in water) may be used as a base for pH adjustment to obtain hexagonal mesoporous aluminophosphate (TAP).
Tetramethylammonium hydroxide is a quaternary ammonium salt generally used as an anisotropic etchant for silicon due to its high silicon etching rate.


1 L in glass bottle
250 mL in glass bottle

Signal Word


Hazard Classifications

Acute Tox. 2 Dermal - Acute Tox. 2 Oral - Aquatic Chronic 2 - Eye Dam. 1 - Skin Corr. 1 - STOT RE 1 Dermal - STOT SE 1

Target Organs

Central nervous system

Storage Class Code

6.1B - Non-combustible, acute toxic Cat. 1 and 2 / very toxic hazardous materials



Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Personal Protective Equipment

dust mask type N95 (US),Eyeshields,Gloves

Certificate of Analysis

Certificate of Origin

Synthesis of mesoporous hexagonal titanium aluminophosphate molecular sieves and their catalytic applications
Kapoor MP & Raj A.
Applied Catalysis A: General, 203(2), 311-319 (2000)
Study on anisotropic silicon etching characteristics in various surfactant-added tetramethyl ammonium hydroxide water solutions.
Yang CR, et al.
Journal of Micromechanics and Microengineering, 15(11), 2028-2028 (2005)
The characteristic behavior of TMAH water solution for anisotropic etching on both silicon substrate and SiO 2 layer.
Chen PH, et al.
Sensors and actuators A, Physical, 93(2), 132-137 (2001)
Magdalena Borkowska et al.
Nature nanotechnology, 15(4), 331-341 (2020-03-24)
Lysosomes have become an important target for anticancer therapeutics because lysosomal cell death bypasses the classical caspase-dependent apoptosis pathway, enabling the targeting of apoptosis- and drug-resistant cancers. However, only a few small molecules-mostly repurposed drugs-have been tested so far, and
Man Xu et al.
Environmental science & technology, 47(1), 110-118 (2012-06-12)
Elucidating dissolution kinetics and mechanisms at carbonate mineral-water interfaces is essential to many environmental and geochemical processes, including geologic CO(2) sequestration in deep aquifers. In the present work, effects of background electrolytes on dolomite (CaMg(CO(3))(2)) reactivity were investigated by measuring

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