Dimesylate

Dimesylate is a term used in chemistry to denote a salt or ester containing two methanesulfonate (mesylate) groups. In practice, it most commonly refers to the bis(mesylate) salt of a cationic species, where two methanesulfonate counterions balance a doubly positively charged center. The mesylate anion (CH3SO3−) originates from methanesulfonic acid and serves as a leaving group in organic synthesis as well as a counterion in salt formation.

In pharmaceutical and materials contexts, a dimesylate often describes a compound where a drug molecule carrying two positive charges is paired with two mesylate anions. This can influence properties such as solubility, stability, and hygroscopicity, and is used to improve formulation characteristics or crystallinity. The term can also refer to a compound possessing two mesylate ester groups, but the salt form with two counterions is the more common usage.

Preparation typically involves salt formation with two equivalents of methanesulfonic acid or a metathesis reaction that replaces other counterions with mesylate on a dicharged substrate. Dimesylates are generally water-soluble and should be handled with care, as methanesulfonic acid is a strong, corrosive reagent; standard cautions for handling corrosive acids apply.

See also mesylate, methanesulfonic acid, sulfonate esters, salt formation.