Methanesulfonic acid (MsOH) or methanesulphonic acid (in British English) is an
organosulfuric, colorless liquid with the
chemical formula
In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...
and
structure
A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such a ...
. It is the simplest of the
alkylsulfonic acids ().
Salts and
ester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...
s of methanesulfonic acid are known as
mesylates (or methanesulfonates, as in
ethyl methanesulfonate). It is
hygroscopic
Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance' ...
in its concentrated form. Methanesulfonic acid can dissolve a wide range of metal salts, many of them in significantly higher
concentration
In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', ''number concentration'', ...
s than in
hydrochloric acid
Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dige ...
(HCl) or
sulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
().
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 (BH
3) by reacting methanesulfonic acid with
NaBH4 in an aprotic solvent such as
THF
Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water-miscible organic liquid with low viscosity. It is ma ...
or
DMS, the complex of BH
3 and the solvent is formed.
Electroplating
Solutions of methanesulfonic acid are used for the electroplating of tin and tin-lead solders. It is displacing the use of
fluoroboric acid
Fluoroboric acid or tetrafluoroboric acid (archaically, fluoboric acid) is an inorganic compound with the chemical formula +BF4−], where H+ represents the solvated proton. The solvent can be any suitably Lewis-basic entity. For instance, in w ...
, which releases corrosive and volatile
hydrogen fluoride.
Methanesulfonic acid is also a primary ingredient in rust and scale removers.
It is used to clean off surface rust from ceramic, tiles and porcelain which are usually susceptible to acid attack.
See also
*
Trifluoromethanesulfonic acid - the more acidic trifluoro analogue
References
{{Authority control
Sulfonic acids
Reagents for organic chemistry
Acid catalysts
Organic compounds with 1 carbon atom