ArOSO3

ArOSO3 denotes a class of aryl sulfonate esters in organic chemistry, where an aryl group (Ar) is connected through an oxygen-sulfonyl linkage to a sulfonate moiety. In practical terms, these compounds are formed when an alcohol reacts with arylsulfonyl chlorides or with sulfur trioxide complexes to give RO-SO2-Ar or Ar-OSO2-R structures, depending on the exact reagents. The key feature is that the sulfonate fragment serves as a good leaving group in subsequent reactions, making aryl sulfonate esters valuable in synthesis.

Common examples of aryl sulfonate esters include tosylates (tosyl = p-toluenesulfonyl), nosylates (nosyl = 2-nitrobenzenesulfonyl), and mesylates (mesyl = methanesulfonyl) when the aryl or sulfonyl component is chosen accordingly. Among these, the tosylate group is widely used to convert alcohols into excellent leaving groups for nucleophilic substitution and elimination reactions, enabling transformations such as SN1/SN2 substitutions and E2 eliminations under mild conditions. Nosylates serve as alternative leaving groups with different steric and electronic properties and can be removed under specific conditions to reveal the original alcohol.

Preparation typically involves reacting an alcohol with a sulfonyl chloride (for example, ArSO2Cl) in the presence of a base, or treating a phenol with a sulfur trioxide complex, to form the aryl sulfonate ester. Properties of aryl sulfonates vary with the aryl group and sulfonyl moiety; they are generally stable solids or liquids, often crystalline, and commonly used in protecting-group strategies as well as in diverse organic synthesis steps.

See also: tosylate, nosylate, mesylate, sulfonyl chlorides, protecting groups.