Monoadducts

Monoadducts are products of a reaction in which one molecule of an adduct-forming reagent attaches to a substrate, creating a single new bond or attachment site. The term is used across chemistry to distinguish from bisadducts and higher-order adducts, where two or more addends become attached either on the same substrate or at different sites.

In organic chemistry, monoadduct formation commonly occurs during electrophilic addition to unsaturated substrates or during radical, nucleophilic, or cycloaddition processes where only one instance of addition has occurred under the given conditions. If additional equivalents of reagent are present or the substrate can undergo secondary reactions, monoadducts may convert into di- or polyadducts.

In biochemistry and toxicology, adducts formed between reactive chemicals and biomolecules (for example DNA, proteins, or glutathione) can initially appear as monoadducts; subsequent reactions can generate additional adducts or crosslinks. Monoadducts can thus provide information about exposure and the reactivity of a chemical toward biological substrates.

Analysis and significance: The identification and quantification of monoadducts can shed light on reaction mechanisms, the extent of modification, or the potential for further reaction. Techniques used to study them include chromatography, mass spectrometry, and various spectroscopic methods. In summary, monoadducts denote single-attachment products and are a useful descriptor across disciplines to indicate the potential for subsequent modification.