Addukt

Addukt, often written adduct in English, is a chemical species formed when two or more reactants combine to yield a single product. The term is used across organic, inorganic, and biochemistry contexts. Adduct formation can occur by addition to a multiple bond, by condensation to form a new linkage, or by coordination between a Lewis acid and a Lewis base. In some languages, including German and Dutch, the spelling addukt is common and refers to the same concept.

Adducts are commonly classified as covalent adducts, which involve the formation of new covalent bonds (for example, biomolecule adducts formed when reactive metabolites bind to DNA or proteins), and noncovalent or coordination adducts, which are stabilized by donor–acceptor interactions such as Lewis acid–base bonds. Cycloadducts are products of cycloaddition reactions and are also referred to as adducts.

Formation mechanisms vary: nucleophilic or electrophilic addition to unsaturated substrates, condensation between functional groups with the loss of a small molecule, or the formation of a coordination complex between a Lewis acid and a base.

Examples include cyanohydrins formed from aldehydes and hydrogen cyanide, gem-diol adducts from the hydration of carbonyls, Diels–Alder cycloadducts, boron trifluoride–ether coordination adducts, and biomolecule adducts such as DNA adducts resulting from reactive metabolites. Understanding adduct formation is important in mechanism elucidation, analytical chemistry, pharmacology, and toxicology.