C6H4OH2

C6H4OH2 is a condensed way to refer to dihydroxybenzenes, compounds in which a benzene ring bears two hydroxyl (OH) groups. The three positional isomers are ortho- (1,2-dihydroxybenzene, called catechol), meta- (1,3-dihydroxybenzene, resorcinol), and para- (1,4-dihydroxybenzene, hydroquinone). All share the molecular formula C6H6O2.

These compounds occur in nature and are produced commercially as important chemical intermediates. Catechol can arise in oxidation processes in plants and serves as a building block in organic synthesis. Resorcinol and hydroquinone are prepared industrially by various routes from phenol or related benzene derivatives, and they serve as precursors for polymers, resins, dyes, antioxidants, and cosmetic ingredients.

Properties of the dihydroxybenzene family include polarity and the ability to form hydrogen bonds due to the two hydroxyl groups. They are typically colorless solids or liquids at room temperature and show varying aqueous solubility. They can undergo oxidation to benzoquinone derivatives and are susceptible to further chemical transformations used in organic synthesis.

Applications span multiple industries. Catechol is used as a biochemical reagent and intermediate in polymer and adhesive chemistry. Resorcinol finds use in phenolic resins, dyes, cosmetics, and pharmaceutical intermediates. Hydroquinone is employed in photography and as a skin-lightening agent in some cosmetic products, as well as an antioxidant in rubber and polymer formulations.

Safety and handling considerations are important: these compounds can irritate the skin and eyes and may pose health and environmental risks. Proper protective equipment and containment practices are recommended, with regulations varying by country.