Mesylate
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In organosulfur chemistry, a mesylate is any salt or ester of methanesulfonic acid (Template:Chem2). In salts, the mesylate is present as the Template:Chem2 anion. When modifying the international nonproprietary name of a pharmaceutical substance containing the group or anion, the spelling used is sometimes mesilate (as in imatinib mesilate, the mesylate salt of imatinib).<ref>Template:Cite report</ref>
Mesylate esters are a group of organic compounds that share a common functional group with the general structure Template:Chem2, abbreviated Template:Chem2, where R is an organic substituent. Mesylate is considered a leaving group in nucleophilic substitution reactions.<ref>Template:Cite book</ref>
Preparation
Mesylate esters are generally prepared by treating an alcohol and methanesulfonyl chloride in the presence of a base, such as triethylamine.<ref>Template:OrgSynth (a procedure illustrating the use of mesylates).</ref>
Mesyl
Related to mesylate is the mesyl (Ms) or methanesulfonyl (Template:Chem2) functional group. The shortened term itself was coined by Helferich et al. in 1938 similarly to tosyl adopted earlier.<ref>Template:Cite journal</ref> Methanesulfonyl chloride is often referred to as mesyl chloride.
Whereas mesylates are often hydrolytically labile, mesyl groups, when attached to nitrogen, are resistant to hydrolysis.<ref>Template:Cite book</ref> This functional group appears in a variety of medications, particularly cardiac (antiarrhythmic) drugs, as a sulfonamide moiety. Examples include sotalol, ibutilide, sematilide, dronedarone, dofetilide, E-4031, and bitopertin.Template:Citation needed
Pharmaceutical preparations
Mesylate salts are often used in preparing the dosage forms of basic drugs. Mesylate salts often yield a higher solubility, and may also excel in other pharmaceutically-relevant factors such as hygroscopicity, clean polymorphic profile, particle size, and flow properties.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Natural occurrence
Ice core samples from a single spot in Antarctica were found to have tiny inclusions of magnesium methanesulfonate dodecahydrate. This natural phase is recognized as the mineral ernstburkeite. It is extremely rare.<ref>Template:Cite journal</ref><ref>Template:Mindat</ref>