Sulfenyl

Sulfenyl is a functional-group designation used in organosulfur chemistry to denote the sulfur-centered substituent RS–. In many compounds the sulfenyl unit serves as a linking group between two carbon fragments, giving thioethers (sulfides) of the form R–S–R′. The term also describes a class of reagents in which the RS– fragment is transferred to a substrate, producing sulfenylated products.

Naming and scope: The sulfenyl group is the substituent derived from a thiol by removal of hydrogen. When attached to a carbon framework, the fragment is often described as a sulfenyl substituent, for example a phenylsulfenyl group (PhS–) or a p-tolylsulfenyl group. Reagents that contain the RS– linkage, such as sulfenyl chlorides (R–S–Cl), are used to introduce sulfenyl groups in organic synthesis.

Reactivity and applications: Sulfenylating reactions transfer RS groups to nucleophiles or radicals, enabling formation of aryl- or alkyl sulfides, R–S–R′, or related derivatives. Sulfenyl chlorides and related reagents are common tools for thioether synthesis, while sulfenyl radicals derived from RS–X sources participate in radical sulfenylation of alkenes and arenes. The sulfenyl group is distinct from related sulfur functionalities such as thiols (R–SH), sulfides (R–S–R′), sulfoxides (R–S(O)–R′), and sulfones (R–S(O)2–R′).

See also sulfur chemistry and organosulfur functional groups.