Sulfinate

A sulfinate is the conjugate base of a sulfinic acid and, more broadly, a class of salts or esters derived from sulfinic acids. The general organic sulfinate anion has the form R-S(O)2-O−, where R is hydrogen or an organic substituent. When R is hydrogen, the compound is hydrogen sulfinate; with an organic R, the compound is an organic sulfinate. The salts of these anions are commonly referred to as sulfinate salts.

Sulfinate species occur in both inorganic and organosulfur chemistry. Common examples of salts include sodium benzenesulfinate and sodium methanesulfinate. The sulfur atom in these salts bears a sulfinyl group (S(VI)) with two highly polarized S=O bonds, and the negative charge is delocalized over the two oxygens. These compounds are typically stable solids or liquids and are usually highly soluble in polar solvents.

Preparation of sulfinate salts is typically achieved by neutralization of sulfinic acids with bases. Sulfinic acids themselves can be prepared by established routes in sulfur chemistry, including oxidation-related methods from thio compounds or other sulfur-containing precursors. In practice, a wide range of aryl and alkyl sulfinates are prepared to serve as reagents in organic synthesis.

In organic synthesis, sulfinate salts act as nucleophiles and as sources of the sulfinyl group (SO2R). They are used to install sulfinyl functionalities into molecules, and can serve as precursors to sulfones, sulfonates, or other sulfur-containing motifs through subsequent oxidation, substitution, or coupling steps. Their utility spans areas such as sulfur-alkylation, sulfinyl transfer, and the preparation of diverse sulfur-containing compounds.

See also: sulfinic acid, sulfite, sulfone, sulfonyl group.