Methanesulfonic acid

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 sulfuric acid.[3]

Methanesulfonic acid
Names
IUPAC name
Methanesulfonic acid
Other names
Methylsulfonic acid, MSA
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.000.817
EC Number
  • 200-898-6
UNII
Properties
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
miscible
Solubility Miscible with methanol, diethyl ether.
Immiscible with hexane
log P -2.424[1]
Acidity (pKa) −1.9[2]
Hazards
Safety data sheet Oxford MSDS
Harmful (Xn), Corrosive (C)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

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. It 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]

Electroplating

Solutions of methanesulfonic acid are used for the electroplating of tin and tin-lead soldiers. It is displacing the use of fluoroboric acid, which releases corrosive and volatile hydrogen fluoride.[5]

Methanesulfonic acid is also a primary ingredient in rust and scale removers.[6] It is used to clean off surface rust from ceramic, tiles and porcelain which are usually susceptible to acid attack.

References
  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.
  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. Process Res. Dev. 8: 1072. doi:10.1021/op049910h.
  5. Balaji, R.; Pushpavanam, Malathy (2003). "Methanesulphonic acid in electroplating related metal finishing industries". Transactions of the Imf. 81 (5): 154–158. doi:10.1080/00202967.2003.11871526.
  6. "Archived copy" (PDF). Archived from the original (PDF) on 2016-03-04. Retrieved 2015-12-01.CS1 maint: archived copy as title (link)
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