odiphenols

O-diphenols, or ortho-diphenols, are chemical compounds that contain two phenolic hydroxyl groups attached to adjacent carbon atoms on a benzene ring (positions 1 and 2). The simplest member is 1,2-dihydroxybenzene, commonly known as catechol. Other o-diphenols are substituted derivatives in which the two hydroxyl groups remain adjacent to each other.

In biology and chemistry, o-diphenols are important as substrates for enzymes such as tyrosinase, which oxidizes them to o-quinones in pathways like melanin formation. Catechol is also related to catecholamines, where the catechol moiety is a key functional group. O-diphenols occur in many plant polyphenols and can act as antioxidants, redox mediators, and precursors to pigments.

Chemically, o-diphenols are relatively readily oxidized, particularly on exposure to air or enzymatic systems, to form o-quinones. These reactive quinones can undergo further reactions, including polymerization and conjugation with nucleophiles such as amines or thiols, leading to pigments or polymers. Substitution patterns on the ring influence redox potential and the stability of the resulting quinones.

Industrial and research relevance includes use as antioxidants, in polymer chemistry, and as building blocks for dyes and resin precursors. In bioinspired materials, o-diphenol motifs (notably in dopamine) are utilized for surface adhesion and coating formation via oxidative crosslinking.