Methanesulfonic acid

Methanesulfonic acid
Structural formula	Ball-and-stick model
Names
	IUPAC name Methanesulfonic acid
	Other names Methylsulfonic acid, MSA
Identifiers
CAS Number	75-75-2 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:27376 ;
ChemSpider	6155 ;
ECHA InfoCard	100.000.817
EC Number	200-898-6;
PubChem CID	6395;
UNII	12EH9M7279 ;
CompTox Dashboard (EPA)	DTXSID4026422 ;
	InChI InChI=1S/CH4O3S/c1-5(2,3)4/h1H3,(H,2,3,4) Key: AFVFQIVMOAPDHO-UHFFFAOYSA-N ; InChI=1/CH4O3S/c1-5(2,3)4/h1H3,(H,2,3,4)/f/h2H; InChI=1/CH4O3S/c1-5(2,3)4/h1H3,(H,2,3,4) Key: AFVFQIVMOAPDHO-UHFFFAOYAS;
	SMILES O=S(=O)(O)C;
Properties
Chemical formula	CH4O3S
Molar mass	96.10 g·mol−1
Appearance	Clear liquid
Density	1.48 g/cm3
Melting point	17 to 19 °C (63 to 66 °F; 290 to 292 K)
Boiling point	167 °C (333 °F; 440 K) at 10 mmHg, 122 °C/1 mmHg
Solubility in water	miscible
Solubility	Miscible with methanol, diethyl ether. ; Immiscible with hexane
log P	-2.424
Acidity (pKa)	−1.9
Hazards
Safety data sheet (SDS)	Oxford MSDS
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

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. Methanesulfonic acid may be considered an intermediate compound between sulfuric acid (H₂SO₄), and methylsulfonylmethane ((CH₃)₂SO₂), effectively replacing an –OH group with a –CH₃ group at each step. This pattern can extend no further in either direction without breaking down the –SO₂– group. Methanesulfonic acid can dissolve a wide range of metal salts, many of them in significantly higher concentrations than in hydrochloric or sulphuric acid.^[3]

Applications

Methanesulfonic acid is used as an acid catalyst in organic reactions because it is a non-volatile, strong acid that is soluble in organic solvents. Methanesulfonic acid is convenient for industrial applications because it is liquid at ambient temperature, while the closely related p-toluenesulfonic acid (PTSA) is solid. However, in a laboratory setting, solid PTSA is more convenient.

Methanesulfonic acid can be used in the generation of borane (BH₃) by reacting methanesulfonic acid with NaBH₄ in an aprotic solvent such as THF or DMS, the complex of BH₃ and the solvent is formed.^[4]

Methanesulfonic acid is considered a particularly suitable supporting electrolyte for electrochemical applications, where it stands as an environmentally friendly alternative to other acid electrolytes used in plating processes.^[3] Methanesulfonic acid is also the electrolyte of choice in zinc-cerium (see cerium(III) methanesulfonate) and lead-acid (methanesulfonate) flow batteries.

Methanesulfonic acid is also a primary ingredient in rust and scale removers.^[5] It is used to clean off surface rust from ceramic, tiles and porcelain which are usually susceptible to acid attack.

References

^ Towler, Christopher S.; Li, Tonglei; Wikström, Håkan; Remick, David M.; Sanchez-Felix, Manuel V.; Taylor, Lynne S. (December 2008). "An Investigation into the Influence of Counterion on the Properties of Some Amorphous Organic Salts". Molecular Pharmaceutics. 5 (6): 946–955. doi:10.1021/mp8000342.
^ Guthrie, J. Peter (September 1978). "Hydrolysis of esters of oxy acids: pKa values for strong acids; Brønsted relationship for attack of water at methyl; free energies of hydrolysis of esters of oxy acids; and a linear relationship between free energy of hydrolysis and pKa holding over a range of 20 pK units". Canadian Journal of Chemistry. 56 (17): 2342–2354. doi:10.1139/v78-385.
^ ^a ^b Gernon, M. D.; Wu, M.; Buszta, T.; Janney, P. (1999). "Environmental benefits of methanesulfonic acid: comparative properties and advantages". Green Chemistry. 1 (3): 127–140. doi:10.1039/a900157c.
^ Lobben, Paul C.; Leung, Simon Shun-Wang; Tummala, Srinivas (2004). "Integrated Approach to the Development and Understanding of the Borane Reduction of a Carboxylic Acid". Org. Proc. Res. Dev. 8: 1072. doi:10.1021/op049910h.
^ http://prep-productions.com/msds/marathon_scale_and_rust_remover.pdf

[1] Towler, Christopher S.; Li, Tonglei; Wikström, Håkan; Remick, David M.; Sanchez-Felix, Manuel V.; Taylor, Lynne S. (December 2008). "An Investigation into the Influence of Counterion on the Properties of Some Amorphous Organic Salts". Molecular Pharmaceutics. 5 (6): 946–955. doi:10.1021/mp8000342.

[2] Guthrie, J. Peter (September 1978). "Hydrolysis of esters of oxy acids: pKa values for strong acids; Brønsted relationship for attack of water at methyl; free energies of hydrolysis of esters of oxy acids; and a linear relationship between free energy of hydrolysis and pKa holding over a range of 20 pK units". Canadian Journal of Chemistry. 56 (17): 2342–2354. doi:10.1139/v78-385.

[Gernon-3] Gernon, M. D.; Wu, M.; Buszta, T.; Janney, P. (1999). "Environmental benefits of methanesulfonic acid: comparative properties and advantages". Green Chemistry. 1 (3): 127–140. doi:10.1039/a900157c.

[4] Lobben, Paul C.; Leung, Simon Shun-Wang; Tummala, Srinivas (2004). "Integrated Approach to the Development and Understanding of the Borane Reduction of a Carboxylic Acid". Org. Proc. Res. Dev. 8: 1072. doi:10.1021/op049910h.

[5] ttp://prep-productions.com/msds/marathon_scale_and_rust_remover.pdf

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