MercaptanGruppen

MercaptanGruppen, in chemistry commonly referred to as thiol groups, are sulfur-containing functional groups characterized by the structure –SH attached to a carbon skeleton (R–SH). The term mercaptan is traditional; the systematic name thiol is preferred in modern usage. Thiol groups are typically weakly acidic (pKa around 10–11 for simple aliphatic thiols in water) and are nucleophilic at sulfur.

Reactivity and properties: Thiols readily oxidize to form disulfides (R–S–S–R), a reaction central to protein folding and materials chemistry. They can coordinate to metals as soft ligands and participate in various substitution and alkylation reactions to form thioethers (R–S–R′). Due to the sulfur atom, thiols often exhibit strong, characteristic odors even at very low concentrations.

Occurrence and applications: Thiol groups occur widely in natural and synthetic compounds. A notable application is odorization of odorless natural gas, using compounds such as ethyl mercaptan or tert-butylthiol to enable leak detection. In biochemistry, cysteine provides a thiol side chain crucial for disulfide bond formation and protein structure. Thiol functionality also features in coenzyme A and other biomolecules. In polymer chemistry, thiols serve as chain transfer agents and can influence radical polymerization processes. They can be transformed into various sulfur-containing motifs, including thioethers and disulfides, through straightforward reactions.

Safety and nomenclature: Many mercaptans are highly odiferous and can be irritants or toxic at higher exposures; they are typically flammable and require proper handling. In nomenclature, the suffix –thiol denotes the compound, while mercaptan is the historical name and mercapto- the substitutive prefix.