orthodihydroxy

Orthodihydroxy, often written as o-dihydroxy or ortho-dihydroxy, is a chemical descriptor used in organic chemistry to indicate two hydroxyl (-OH) groups attached to neighboring carbon atoms in a molecule, most commonly on an aromatic ring. The defining example is catechol, or 1,2-dihydroxybenzene, where the hydroxyls occupy adjacent positions on the benzene ring. In substituted arenes, the ortho-dihydroxy motif describes two adjacent hydroxyls in relation to a reference substituent and is often designated as dihydroxy at positions 1 and 2.

Properties and reactivity: The ortho arrangement enables intramolecular hydrogen bonding and can influence conformation and reactivity. The o-dihydroxy motif is prone to oxidation to o-quinones and can strongly chelate metal ions, contributing to antioxidant behavior, catalytic activity, and redox chemistry in both biological and material contexts.

Occurrence and significance: Catechol motifs are widespread in natural products and biomolecules. In biochemistry, derivatives with orthodihydroxy groups appear in catecholamines such as dopamine, where adjacent hydroxyls on the benzene ring influence color, reactivity, and biological activity. In industry and research, orthodihydroxy compounds are used as building blocks for polymers, dyes, and coordination complexes, owing to their chelating and redox properties.

See also: o-dihydroxy, catechol, hydroquinone, resorcinol.