ROSO2CH3

ROSO2CH3 denotes alkyl methanesulfonate esters, commonly called mesylates. They have the general structure R-O-SO2-CH3, where R represents an alkyl or aryl group. Mesylates are the esters formed from methanesulfonic acid and an alcohol, and they function as activated leaving groups in organic synthesis.

Synthesis and structure

Mesylates are typically prepared by reacting an alcohol (ROH) with methanesulfonyl chloride (MsCl) in the presence of a base, yielding ROSO2CH3 and a salt such as HCl. The key feature is the -OSO2CH3 leaving group, which imparts high reactivity for substitution reactions.

Properties

Mesylates are generally polar and can be liquids or solids depending on the R group. They are soluble in many polar solvents and are moisture-sensitive, tending to hydrolyze in the presence of water to recover the original alcohol and methanesulfonic acid. As leaving groups, mesylates are typically more effective than many other alkyl esters in SN2 processes, while still being compatible with a range of nucleophiles.

Reactions and applications

ROSO2CH3 compounds serve to convert poor alcohol leaving groups into good ones, enabling subsequent nucleophilic substitution to form ethers, amines, thioethers, or other products. They are widely used to activate alcohols for SN1/SN2 reactions and to prepare ethers, amines, and related derivatives. In medicinal and synthetic chemistry, mesylates are valued for their versatility and relatively straightforward preparation. Notable derivatives such as methyl methanesulfonate (MMS) and ethyl methanesulfonate (EMS) are recognized as potent alkylating agents with mutagenic and carcinogenic hazards, necessitating strict safety controls.

Safety

Handle mesylates with appropriate personal protective equipment in well-ventilated areas. Some mesylates are hazardous and require careful risk assessment and compliant waste disposal practices. Always consult the SDS for specific compounds.

See also

Mesylate; Methanesulfonic acid; Tosylate.