Methane Sulfonic acid

Cas Number


Other Names

Methylsulfonic acid, MSA

The formula



Methanesulfonic acid (MsOH) is a colorless liquid with the chemical formula CH3SO3H. It is the simplest of the alkylsulfonic acids. Salts and esters of methanesulfonic acid are known as mesylates (or methanesulfonates, as in ethyl methanesulfonate). It is hygroscopic in its concentrated form.

Physical and Chemical Properties
Physical state and appearance Colorless or light yellow liquid
Molecular Weight 96.11 g mol
pH (1% soln/water) Neutral.
Color Clear Colorless
Boiling Point The lowest known value is 100°C (212°F) (Water)
Flash point 60°C
Melting Point May start to solidify at 20°C (68°F) based on data for:
Specific Gravity Weighted average: 1.3 (Water = 1)
Vapor Pressure: The highest known value is 17.535 mm of Hg (@ 20°C) (Water).
Vapor Density The highest known value is 3.31 (Air = 1) Weighted average: 2.5(Air = 1)
Dispersion Properties See solubility in water.
Solubility Easily soluble in cold water, hot water
Purity 99% min.
Methyl methane sulfonate (MSA methyl ester) 50 ppm max.
Cl- 50 ppm max.
Fe2+ 10 ppm max.
Heavy metals 10 ppm max.
Oxidizable compounds 20 ppm max.
SO42- content 250 ppm max.

Electroplating and electrochemical processes

1. Alkylation, esterification and condensation reactions

2. Lead recovery

3. Chemical intermediate for manufacture of drugs and pesticides

4. Petroleum refining and lube oil additives

5. Extraction and process solvent

6. Plastic stabilizers