RSO3R

RSO3R is a generic representation used in chemistry to denote sulfonate esters, a class of organosulfur compounds formed by esterification of a sulfonic acid with an alcohol. In these compounds the sulfonyl group is bonded to two substituents, typically an R group directly on sulfur and an OR' group derived from the alcohol, often written as R-S(=O)2-O-R'. The term RSO3R serves as a placeholder for a variety of specific sulfonate esters, such as tosylates, mesylates, and nosylates.

Common examples include tosylates (p-toluenesulfonates), where the R group is a p-tolyl moiety, and mesylates (methanesulfonates), where R is a methyl group. Nosylates refer to p-nitrobenzenesulfonates. These compounds are widely used in organic synthesis as leaving groups, because they form relatively stable anions after displacement, enabling efficient nucleophilic substitution or elimination.

Preparation of sulfonate esters typically involves reacting an alcohol (ROH) with a sulfonyl chloride (RSO2Cl) or a sulfonic anhydride in the presence of a base, yielding the sulfonate ester RO-SO2-R' and byproducts such as HCl. The choice of R and R' can influence the solubility, stability, and leaving-group ability of the resulting ester.

Applications span SN1 and SN2 reactions, carbohydrate chemistry, peptide synthesis, and polymer chemistry, where sulfonate esters serve as versatile, tunable leaving groups. See also tosylate, mesylate, and nosylate for common, named examples.