Dihydroxybenzene

Dihydroxybenzene refers to any chemical compound derived from benzene that bears two hydroxyl (-OH) groups on the ring. The three main positional isomers are catechol (1,2-dihydroxybenzene, often called o-dihydroxybenzene), resorcinol (1,3-dihydroxybenzene, or m-dihydroxybenzene), and hydroquinone (1,4-dihydroxybenzene, or p-dihydroxybenzene). All three share the same molecular formula, C6H4(OH)2, but differ in the relative positions of the hydroxyl groups, which affects their chemical properties and reactivity.

These compounds are generally colorless solids or crystals and are weakly acidic phenols that can be oxidized readily. Upon oxidation, each isomer forms a corresponding benzoquinone: catechol yields o-benzoquinone, resorcinol yields m-benzoquinone, and hydroquinone yields p-benzoquinone. They are more reactive toward electrophilic substitution than benzene due to the activating effect of the two hydroxyl groups, and they form various derivatives used in chemical synthesis.

Occurrence and production are limited in nature, with these compounds typically synthesized for industrial use. They can be produced from phenol or related precursors and via oxidation or reduction routes involving benzoquinones or catechol-like intermediates. Their solubility in water varies by isomer, and they are generally handled as irritants.

Uses are diverse: as chemical intermediates in the manufacture of polymers, dyes, pharmaceuticals, and antioxidants; hydroquinone, in particular, has historical use as a photographic developing agent and as a cosmetic skin-lightening agent. Catechol and resorcinol likewise serve as precursors in resin and dye chemistry. Safety considerations include their irritant and potentially toxic nature, requiring appropriate protective equipment and handling procedures.