What Is a Catechol?
Catechol, also known as 1,2-benzenediol, 1,2-dihydroxybenzene, pyrocatechol, or blenzcatechin, is a type of divalent phenol. It appears as colorless ridge columnar crystals and is known for its diverse applications in various fields.
Uses of Catechol
Catechol is utilized in several ways, including as a developing agent for photographs in combination with p-methylaminophenol. Its ability to form complexes with metals like titanium, molybdenum, iron, and cobalt in alkaline solutions makes it a valuable reagent for analyzing metal ions. Moreover, it finds use as an antioxidant, a plating additive, a polymerization inhibitor, a rubber vulcanizer, and an intermediate raw material for medical and agrochemical products. Additionally, catechol melanin, formed by oxidative polymerization of catechol, is used as an insoluble black pigment.
Properties of Catechol
Catechol is known for its tendency to easily sublimate. It has a melting point of 221°F (105°C) and a boiling point of 474°F (245.5°C). It is soluble in water, alcohols, and ethers, and is easily oxidized, especially in alkaline solutions, leading to discoloration. In vivo, catechol forms a redox system with o-quinone and acts as one of the electron transfer systems. It also demonstrates reducing power, reducing Fehling’s solution, and exhibiting a silver mirror reaction.
Structure of Catechol
Catechol is an organic compound with two hydroxy groups situated at the ortho position on a benzene ring, categorized as a polyphenol structure. Its chemical formula is C6H6O2 with a molar mass of 110.1 g/mol and a specific formula of C6H4(OH)2. Its density is 1.344 g/cm³. Catechol is a positional isomer of hydroquinone and resorcinol, which have their hydroxy groups in different positions on the benzene ring.
Other Information on Catechol
1. Synthesis of Catechol
Catechols can be produced through several methods, such as the alkaline fusion of lignin or tannin, or by reducing o-benzoquinone. Alternative synthesis methods include alkali fusion of o-chlorophenol or demethylation of guaiacol.
2. Biomaterials Containing a Catechol Backbone
Catechol serves as the backbone for various biomolecules. Notable examples include catecholamines like dopamine, levodopa (L-3,4-dihydroxyphenylalanine), adrenaline, and noradrenaline. The catechol backbone is also present in polyphenols such as urushiol and catechin, which are the main constituents in lacquer.
3. Positional Isomers of Catechol
Catechol’s regiomers include hydroquinone and resorcinol. Hydroquinone, or 1,4-dihydroxybenzene, features two hydroxy groups in the para position of the benzene ring. Resorcinol, or 1,3-dihydroxybenzene, has its hydroxy groups in the meta position. Their respective physical properties, such as density, melting point, and boiling point, distinguish them from catechol.