sulfinic

Sulfinic is an adjective used in chemistry to describe compounds related to the sulfinic acid group or containing the sulfinic functional motif. The core motif is the sulfinic acid moiety, typically written as R-SO2H, in which sulfur is in the +4 oxidation state. The deprotonated form is the sulfinite or sulfinate anion, R-SO2−, and salts of these anions are called sulfinates. The term can also describe related derivatives and structural fragments that share this sulfinic linkage.

In nomenclature and classification, sulfinic compounds include the parent sulfinic acids (R-SO2H) and their derivatives such as sulfinates, esters, and salts. This category is distinct from sulfinyl compounds, which feature the sulfinyl group (R-S(O)-) as part of the molecule, and from sulfonic acids (R-SO3H), in which sulfur is in the +6 oxidation state.

Synthesis and reactivity: Sulfinic acids and sulfinates are used as nucleophiles at sulfur in organic synthesis and serve as intermediates to prepare sulfones and sulfonic acids. They can be formed by oxidation of thiols or thioethers, and can be further oxidized to sulfones or sulfonic acids, or reduced back to thiols. Their conjugate bases are generally water-soluble salts useful in various reaction conditions, and they exhibit reactivity patterns characteristic of sulfur in the +4 oxidation state.

Applications and occurrence: Sulfinic compounds appear in synthetic chemistry as reagents and intermediates, and in certain redox-related biological processes where sulfinic species may be transient. The term is primarily used in chemical literature to describe entities bearing the sulfinic moiety. See also sulfinic acid and sulfinate.