Methanesulfonic anhydride (Ms
2O) is the
acid anhydride
An acid anhydride is a type of chemical compound derived by the removal of water molecules from an acid.
In organic chemistry, organic acid anhydrides contain the functional group . Organic acid anhydrides often form when one equivalent of wa ...
of
methanesulfonic acid
Methanesulfonic acid (MsOH, MSA) or methanesulphonic acid (in British English) is an organosulfuric, colorless liquid with the molecular formula and structure . It is the simplest of the alkylsulfonic acids (). Salts and esters of methanesul ...
. Like
methanesulfonyl chloride
Methanesulfonyl chloride (mesyl chloride) is an organosulfur compound with the formula . Using the organic pseudoelement symbol Ms for the methanesulfonyl (or mesyl) group –, it is frequently abbreviated MsCl in reaction schemes or equations. It ...
(MsCl), it may be used to generate
mesylates
In organosulfur chemistry, a mesylate is any salt or ester of methanesulfonic acid (). In salts, the mesylate is present as the anion. When modifying the international nonproprietary name of a pharmaceutical substance containing the group o ...
(methanesulfonyl esters).
Preparation & purification
Ms
2O may be prepared by the dehydration of
methanesulfonic acid
Methanesulfonic acid (MsOH, MSA) or methanesulphonic acid (in British English) is an organosulfuric, colorless liquid with the molecular formula and structure . It is the simplest of the alkylsulfonic acids (). Salts and esters of methanesul ...
with
phosphorus pentoxide
Phosphorus pentoxide is a chemical compound with molecular formula Phosphorus, P4Oxygen, O10 (with its common name derived from its empirical formula, P2O5). This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desic ...
.
:P
2O
5 + 6 CH
3SO
3H → 3 (CH
3SO
2)
2O + 2 H
3PO
4
Ms
2O can be purified by distillation under vacuum (distillation of a solid) or by recrystallization from
Methyl tert-butyl ether
Methyl ''tert''-butyl ether (MTBE), also known as ''tert''-butyl methyl ether, is an organic compound with a structural formula (CH3)3COCH3. MTBE is a volatile, flammable, and colorless liquid that is sparingly soluble in water. Primarily used a ...
/
toluene
Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon with the chemical formula , often abbreviated as , where Ph stands for the phenyl group. It is a colorless, water
Water is an inorganic compound with the c ...
.
Reactions & Applications in synthesis
Passage of
hydrogen chloride
The Chemical compound, compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hyd ...
through molten Ms
2O yields MsCl.
Similar to MsCl, Ms
2O can perform
mesylation
In organosulfur chemistry, a mesylate is any salt or ester of methanesulfonic acid (). In salts, the mesylate is present as the anion. When modifying the international nonproprietary name of a pharmaceutical substance containing the group o ...
of
alcohols
In chemistry, an alcohol (), is a type of organic compound that carries at least one hydroxyl () functional group bound to a Saturated and unsaturated compounds, saturated carbon atom. Alcohols range from the simple, like methanol and ethanol ...
to form
sulfonates
In organosulfur chemistry, a sulfonate is a salt, anion or ester of a sulfonic acid. Its formula is , containing the functional group , where R is typically an organyl group, amino group or a halogen atom. Sulfonates are the conjugate bases of ...
. Use of Ms
2O avoids the alkyl chloride, which often appears as a side-product when MsCl is used. Unlike MsCl, Ms
2O may not be suitable for mesylation of the
unsaturated alcohols.
Examples of mesylation of alcohols with Ms
2O:
* Octadecyl methanesulfonate was prepared from
octadecanol
Stearyl alcohol, or 1-octadecanol, is an organic compound classified as a saturated fatty alcohol with the formula CH3(CH2)16CH2OH. It takes the form of white granules or flakes, which are insoluble in water. It has a wide range of uses as an i ...
in
pyridine
Pyridine is a basic (chemistry), basic heterocyclic compound, heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom . It is a highly flammable, weak ...
.
* Secondary alcohol at the anomeric carbon of 2,3,4,5-O-
Benzyl
In organic chemistry, benzyl is the substituent or molecular fragment possessing the structure . Benzyl features a benzene ring () attached to a methylene group ().
Nomenclature
In IUPAC nomenclature, the prefix benzyl refers to a substituent ...
-protected
glucose
Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae d ...
reacted to form a glycosyl mesylate, which was found to be more stable than its
triflate
In organic chemistry, triflate (Preferred IUPAC name, systematic name: trifluoromethanesulfonate), is a functional group with the Chemical formula, formula and Chemical structure, structure . The triflate group is often represented by , as opp ...
counterpart, in
2,4,6-collidine
2,4,6-Trimethylpyridine (2,4,6-collidine) is an organic compound which belongs to the Heterocyclic compound, heterocycles (more precisely, Heteroaromatic compound, heteroaromatics). It consists of a pyridine ring substituted with three methyl grou ...
.
Ms
2O also converts
amines
In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...
to
sulfonamides
In organic chemistry, the sulfonamide functional group (also spelled sulphonamide) is an organosulfur group with the Chemical structure, structure . It consists of a sulfonyl group () connected to an amine group (). Relatively speaking this gro ...
.
Aromatic sulfonation
Assisted by
Lewis acid catalyst,
Friedel-Crafts methylsulfonation of
aryl ring can be achieved by Ms
2O. In contrast to MsCl, either
activated or deactivated benzene
Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hyd ...
derivatives can form the corresponding sulfonatesin satisfactory yields with Ms
2O.
Examples of aromatic sulfonation with Ms
2O:
* Sulfonation of
chlorobenzene
Chlorobenzene (abbreviated PhCl) is an aryl chloride and the simplest of the chlorobenzenes, consisting of a benzene ring substituted with one chlorine atom. Its chemical formula is C6H5Cl. This colorless, flammable liquid is a common solvent a ...
resulted in addition of methylsulfonyl group at
para and ortho positions (with respect to chloride), with a ratio of 2 to 1, respectively; while reaction with
Meta-dichlorobenzene gave monosulfonylated product at C4 position.
* With
sulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...
, di-aryl sulfones were synthesized.
Esterification
Ms
2O catalyzes the esterification of alcohols by carboxylic acids.
2-Naphthyl acetate was prepared from
2-naphthol
2-Naphthol, or β-naphthol, is a fluorescent colorless (or occasionally yellow) crystalline solid with the formula C10H7OH. It is an isomer of 1-naphthol, differing by the location of the hydroxyl group on the naphthalene ring. The naphthols are ...
and glacial (anhydrous)
acetic acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...
in the presence of Ms
2O. Both
alcohols
In chemistry, an alcohol (), is a type of organic compound that carries at least one hydroxyl () functional group bound to a Saturated and unsaturated compounds, saturated carbon atom. Alcohols range from the simple, like methanol and ethanol ...
on
ethylene glycol
Ethylene glycol ( IUPAC name: ethane-1,2-diol) is an organic compound (a vicinal diol) with the formula . It is mainly used for two purposes: as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odo ...
successfully
benzoylated with
benzoic acid
Benzoic acid () is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. The benzoyl group is often abbreviated "Bz" (not to be confused with "Bn," which ...
and Ms
2O. However, for free alcohols on
monosaccharides
Monosaccharides (from Greek ''monos'': single, '' sacchar'': sugar), also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built.
Chemically, monosaccharides are polyhydr ...
, the
acetylation
:
In chemistry, acetylation is an organic esterification reaction with acetic acid. It introduces an acetyl group into a chemical compound. Such compounds are termed ''acetate esters'' or simply ''acetates''. Deacetylation is the opposite react ...
was not completed.
Oxidation of alcohols
Like
Pfitzner–Moffatt oxidation
The Pfitzner–Moffatt oxidation, sometimes referred to as simply the Moffatt oxidation, is a chemical reaction for the redox, oxidation of primary and secondary alcohols to aldehydes and ketones, respectively. The oxidant is a combination of dime ...
and
Swern oxidation
In organic chemistry, the Swern oxidation also known as Moffatt-Swern, named after Daniel Swern, is a chemical reaction whereby a primary or secondary Alcohol (chemistry), alcohol () is redox, oxidized to an aldehyde () or ketone () using oxalyl ...
, with
DMSO
Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula . This colorless liquid is the sulfoxide most widely used commercially. It is an important polar aprotic solvent that dissolves both polar and nonpolar compounds and is ...
, Ms
2O can
oxidize
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...
primary
Primary or primaries may refer to:
Arts, entertainment, and media Music Groups and labels
* Primary (band), from Australia
* Primary (musician), hip hop musician and record producer from South Korea
* Primary Music, Israeli record label
Work ...
and
secondary alcohols
In chemistry, an alcohol (), is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. Alcohols range from the simple, like methanol and ethanol, to complex, like sugar alcohols an ...
to
aldehydes
In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...
and
ketones
In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...
, respectively, in
HMPA
Hexamethylphosphoramide, often abbreviated HMPA, is a phosphoramide (an amide of phosphoric acid) with the formula This colorless liquid is used as a solvent in organic synthesis.
Structure and reactivity
HMPA is the oxide of tris(dimethylamino ...
.
This method applies to benzylic alcohol.
HMPA
Hexamethylphosphoramide, often abbreviated HMPA, is a phosphoramide (an amide of phosphoric acid) with the formula This colorless liquid is used as a solvent in organic synthesis.
Structure and reactivity
HMPA is the oxide of tris(dimethylamino ...
may be substituted by
dichloromethane
Dichloromethane (DCM, methylene chloride, or methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odor is widely used as a solvent. Although it is not miscible with ...
but may result in more side-products.
See also
*
Methanesulfonyl chloride
Methanesulfonyl chloride (mesyl chloride) is an organosulfur compound with the formula . Using the organic pseudoelement symbol Ms for the methanesulfonyl (or mesyl) group –, it is frequently abbreviated MsCl in reaction schemes or equations. It ...
*
Disulfuric acid
Disulfuric acid (alternative spelling disulphuric acid) or pyrosulfuric acid (alternative spelling pyrosulphuric acid), also named oleum, is a sulfur oxoacid. It is a major constituent of fuming sulfuric acid, oleum, and this is how most chemists e ...
*
Sodium pyrosulfate
Sodium pyrosulfate is an inorganic compound with the chemical formula of Na2S2O7. It is a colorless salt. It hydrolyses in water to form sodium bisulfate with a chemical formula of NaHSO4 which has a pH of around 1.
Preparation
Sodium pyrosulfat ...
*
Acetic anhydride
Acetic anhydride, or ethanoic anhydride, is the chemical compound with the chemical formula, formula . Commonly abbreviated , it is one the simplest organic acid anhydride, anhydrides of a carboxylic acid and is widely used in the production of c ...
*
Trifluoromethanesulfonic anhydride
Trifluoromethanesulfonic anhydride, also known as triflic anhydride, is the chemical compound with the formula (CF3SO2)2O. It is the acid anhydride derived from triflic acid. This compound is a strong electrophile, useful for introducing the tri ...
References
{{Reflist
Acid anhydrides
Reagents for organic chemistry
Methyl compounds