Small amounts of catechol occur naturally in fruits and vegetables, along with the enzyme polyphenol oxidase (also known as catecholase, or catechol oxidase). (wikipedia.org)
Substrate specificity of catechol oxidase from Lycopus europaeus and characterization of the bioproducts of enzymic caffeic acid oxidation. (lookformedical.com)
Upon mixing the enzyme with the substrate and exposure to oxygen (as when a potato or apple is cut and left out), the colorless catechol oxidizes to reddish-brown melanoid pigments, derivatives of benzoquinone. (wikipedia.org)
Benzoquinone1
An enzyme of the oxidoreductase class that catalyzes the reaction between catechol and oxygen to yield benzoquinone and water. (lookformedical.com)
Reaction1
C6H4(OH)2 + H2O}}} It can be produced by reaction of salicylaldehyde with base and hydrogen peroxide (Dakin oxidation), as well as the hydrolysis of 2-substituted phenols, especially 2-chlorophenol, with hot aqueous solutions containing alkali metal hydroxides. (wikipedia.org)
Water1
Catechol occurs as feathery white crystals that are very rapidly soluble in water. (wikipedia.org)