# Catechol

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Catechol
> Markdown URL: https://mediated.wiki/source/Catechol.md
> Source: https://en.wikipedia.org/wiki/Catechol
> Source revision: 1342294314
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

Organic compound (C6H4(OH)2); benzene with two adjacent –OH groups

Not to be confused with [Catechin](/source/Catechin), also sometimes called catechol.

Catechol Pyrocatechol Ball-and-stick model Names Preferred IUPAC name Benzene-1,2-diol[1] Other names Pyrocatechol[1] 1,2-Benzenediol 2-Hydroxyphenol 1,2-Dihydroxybenzene o-Benzenediol o-Dihydroxybenzene Identifiers CAS Number 120-80-9 Y 3D model (JSmol) Interactive image Beilstein Reference 471401 ChEBI CHEBI:18135 Y ChEMBL ChEMBL280998 Y ChemSpider 13837760 Y DrugBank DB02232 ECHA InfoCard 100.004.025 EC Number 204-427-5 Gmelin Reference 2936 KEGG C00090 Y PubChem CID 289 RTECS number UX1050000 UNII LF3AJ089DQ Y CompTox Dashboard (EPA) DTXSID3020257 InChI InChI=1S/C6H6O2/c7-5-3-1-2-4-6(5)8/h1-4,7-8H Key: YCIMNLLNPGFGHC-UHFFFAOYSA-N SMILES Oc1c(O)cccc1 Properties Chemical formula C6H6O2 Molar mass 110.112 g·mol−1 Appearance white to brown feathery crystals Odor faint, phenolic odor Density 1.344 g/cm3, solid Melting point 105 °C (221 °F; 378 K) Boiling point 245.5 °C (473.9 °F; 518.6 K) (sublimes) Solubility in water 312 g/L at 20 °C[2] Solubility very soluble in pyridine soluble in chloroform, benzene, CCl4, ether, ethyl acetate log P 0.88 Vapor pressure 20 Pa (20 °C) Acidity (pKa) 9.45, 12.8 Magnetic susceptibility (χ) −6.876×10−5 cm3/mol Refractive index (nD) 1.604 Dipole moment 2.62±0.03 D [3] Structure Crystal structure monoclinic Thermochemistry Std enthalpy of formation (ΔfH⦵298) −354.1 kJ·mol−1 Enthalpy of fusion (ΔfH⦵fus) 22.8 kJ·mol−1 (at melting point) Hazards GHS labelling: Pictograms Signal word Danger Hazard statements H301, H311, H315, H317, H318, H332, H341 Precautionary statements P261, P301, P302, P305, P310, P312, P330, P331, P338, P351, P352 NFPA 704 (fire diamond) 3 1 0 Flash point 127 °C (261 °F; 400 K) Autoignition temperature 510 °C (950 °F; 783 K) Explosive limits 1.4%–?[4] Lethal dose or concentration (LD, LC): LD50 (median dose) 300 mg/kg (rat, oral) NIOSH (US health exposure limits): PEL (Permissible) none[4] REL (Recommended) TWA 5 ppm (20 mg/m3) [skin][4] IDLH (Immediate danger) N.D.[4] Safety data sheet (SDS) Sigma-Aldrich Related compounds Related benzenediols Resorcinol Hydroquinone Related compounds 1,2-benzoquinone Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Chemical compound

**Catechol** ([/ˈkætɪtʃɒl/](https://en.wikipedia.org/wiki/Help:IPA/English) or [/ˈkætɪkɒl/](https://en.wikipedia.org/wiki/Help:IPA/English)), also known as **pyrocatechol** or **1,2-dihydroxybenzene**, is an organic compound with the molecular formula C6H4(OH)2. It is the *ortho* [isomer](/source/Isomer) of the three isomeric [benzenediols](/source/Benzenediol). This colorless compound occurs naturally in trace amounts. It was first discovered by [destructive distillation](/source/Destructive_distillation) of the plant extract [catechin](/source/Catechin). About 20,000 tonnes of catechol are now synthetically produced annually as a commodity organic chemical, mainly as a precursor to pesticides, flavors, and fragrances. Small amounts of catechol occur in [fruits](/source/Fruits) and [vegetables](/source/Vegetables).[2]

## Isolation and synthesis

Catechol was first isolated in 1839 by Edgar Hugo Emil Reinsch (1809–1884) by [distilling](/source/Distillation) it from the solid [tannic](/source/Tannin) preparation [catechin](/source/Catechin), which is the residuum of [catechu](/source/Catechu), the boiled or concentrated juice of *Mimosa catechu* (*[Acacia catechu](/source/Acacia_catechu)*).[5] Upon heating catechin above its decomposition point, a substance that Reinsch first named *Brenz-Katechusäure* (burned catechu acid) [sublimated](/source/Sublimation_(phase_transition)) as a white [efflorescence](/source/Efflorescence). This was a thermal decomposition product of the [flavanols](/source/Flavan-3-ol) in catechin. In 1841, both [Wackenroder](/source/Heinrich_Wilhelm_Ferdinand_Wackenroder) and Zwenger independently rediscovered catechol; in reporting on their findings, *[Philosophical Magazine](/source/Philosophical_Magazine)* coined the name *pyrocatechin*.[6] By 1852, [Erdmann](/source/Otto_Linn%C3%A9_Erdmann) realized that catechol was [benzene](/source/Benzene) with two oxygen atoms added to it; in 1867, [August Kekulé](/source/August_Kekul%C3%A9) realized that catechol was a [diol](/source/Diol) of benzene, so by 1868, catechol was listed as *pyrocatechol*.[7] In 1879, the *[Journal of the Chemical Society](/source/Journal_of_the_Chemical_Society)* recommended that catechol be called "catechol", and in the following year, it was listed as such.[8]

Catechol has since been shown to occur in free form naturally in [kino](/source/Pterocarpus_marsupium) and in [beechwood](/source/Beech) tar. Its [sulfonic acid](/source/Sulfonic_acid) has been detected in the [urine](/source/Urine) of horses and humans.[9]

Catechol is produced industrially by the [hydroxylation](/source/Hydroxylation) of [phenol](/source/Phenol) using [hydrogen peroxide](/source/Hydrogen_peroxide).[2]

- C6H5OH + H2O2 → C6H4(OH)2 + H2O

It can be produced by reaction of [salicylaldehyde](/source/Salicylaldehyde) with base and hydrogen peroxide ([Dakin oxidation](/source/Dakin_oxidation)),[10] as well as the [hydrolysis](/source/Hydrolysis) of 2-substituted phenols, especially [2-chlorophenol](/source/2-chlorophenol), with hot aqueous solutions containing alkali metal hydroxides. Its methyl ether derivative, [guaiacol](/source/Guaiacol), converts to catechol via hydrolysis of the CH3−O bond as promoted by [hydroiodic acid](/source/Hydroiodic_acid) (HI).[10]

## Reactions

Like some other difunctional benzene derivatives, catechol readily [condenses](/source/Condensed_tannin) to form [heterocyclic compounds](/source/Heterocyclic_compounds). For example, using [phosphorus trichloride](/source/Phosphorus_trichloride) or [phosphorus oxychloride](/source/Phosphorus_oxychloride) gives the cyclic chloro[phosphonite](/source/Phosphonite) or chloro[phosphonate](/source/Phosphonate), respectively; [sulfuryl chloride](/source/Sulfuryl_chloride) gives the [sulfate](/source/Organosulfate); and [phosgene](/source/Phosgene) (COCl2) gives the [carbonate](/source/Carbonate_ester):[11]

- C6H4(OH)2 + XCl2 → C6H4(O2X) + 2 HCl where X = PCl or POCl; SO2; CO

Basic solutions of catechol react with iron(III) to give the red [Fe(C6H4O2)3]3−. [Ferric chloride](/source/Ferric_chloride) gives a green coloration with the aqueous solution, while the alkaline solution rapidly changes to a green and finally to a black color on exposure to the air.[12] Iron-containing [dioxygenase](/source/Dioxygenase) [enzymes](/source/Enzyme) [catalyze](/source/Catalysis) the [cleavage](/source/Bond_cleavage) of catechol.

### Redox chemistry

Catechols convert to the semiquinone radical. At pH = 7, this conversion occurs at 100 mV:[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*]

- C6H4(OH)2 → C6H4(O)(OH) + ½ H2

The semiquinone radical can be reduced to the catecholate dianion, the potential being dependent on pH:

- C6H4(O)(OH) + e− → [C6H4O2]2− + H+

Catechol is produced by a reversible two-electron, two-proton [reduction](/source/Reduction_potential) of [1,2-benzoquinone](/source/1%2C2-benzoquinone) (*E*0 = +795 mV vs [SHE](/source/Standard_hydrogen_electrode); *E*m (at pH 7) = +380 mV vs SHE).[13]

The [redox](/source/Redox) series catecholate dianion, monoanionic semiquinonate, and benzoquinone are collectively called **dioxolenes**. Dioxolenes can function as [ligands](/source/Ligand) for metal ions.[14]

## Catechol derivatives

	- Naturally occurring catechols

		- [3,4-dihydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione](/source/DHSA), a metabolite of [cholesterol](/source/Cholesterol)[15]

		- [Catechin](/source/Catechin), a component of tea.

		- [Piceatannol](/source/Piceatannol), an antioxidant found in some red wines.

		- [Urushiols](/source/Urushiol), the active agent in [poison ivy](/source/Poison_ivy_(plant)) (R = (CH2)14CH3, (CH2)7CH=CHCH2CH=CHCH2CH=CH2, and others)

		- [Catecholamines](/source/Catecholamine), drugs imitating them (such as [MDMA](/source/MDMA)), [hormones](/source/Hormone)/[neurotransmitters](/source/Neurotransmitter)

		- [Dopamine](/source/Dopamine), a well-known [neurotransmitter](/source/Neurotransmitter) with many important roles in cells

		- [Quercetin](/source/Quercetin), which is found in many foods.

Catechol derivatives are found widely in nature. They often arise by hydroxylation of phenols.[16] [Arthropod](/source/Arthropod) [cuticle](/source/Cuticle) consists of [chitin](/source/Chitin) linked by a catechol [moiety](/source/Moiety_(chemistry)) to [protein](/source/Protein). The cuticle may be strengthened by [cross-linking](/source/Cross-link) ([tanning](/source/Tanning_(leather)) and [sclerotization](/source/Sclerotization)), in particular, in [insects](/source/Insect), and of course by [biomineralization](/source/Biomineralization).[17]

The synthetic derivative [4-*tert*-butylcatechol](/source/4-tert-Butylcatechol) is used as an [antioxidant](/source/Antioxidant) and [polymerization inhibitor](/source/Polymerization_inhibitor).

## Uses

Approximately 50% of the synthetic catechol is consumed in the production of [pesticides](/source/Pesticide), the remainder being used as a precursor to fine chemicals such as perfumes and pharmaceuticals.[2] It is a common building block in [organic synthesis](/source/Organic_synthesis).[18] Several industrially significant [flavors](/source/Flavoring) and [fragrances](/source/Aroma_compound) are prepared starting from catechol. [Guaiacol](/source/Guaiacol) is prepared by [methylation](/source/Methylation) of catechol and is then converted to [vanillin](/source/Vanillin) on a scale of about 10M kg per year (1990). The related monoethyl ether of catechol, [guethol](https://en.wikipedia.org/w/index.php?title=Guethol&action=edit&redlink=1), is converted to [ethylvanillin](/source/Ethylvanillin), a component of [chocolate](/source/Chocolate) confectioneries. 3-*trans*-Isocamphylcyclohexanol, widely used as a replacement for [sandalwood oil](/source/Sandalwood_oil), is prepared from catechol via guaiacol and [camphor](/source/Camphor). [Piperonal](/source/Piperonal), a flowery scent, is prepared from the methylene diether of catechol followed by condensation with [glyoxal](/source/Glyoxal) and [decarboxylation](/source/Decarboxylation).[19]

[Josef Maria Eder](/source/Josef_Maria_Eder) published in 1879 his findings on the use of catechol as a black-and-white [photographic developer](/source/Photographic_developer),[20][21] but, except for some special purpose applications, its use is largely historical. It is rumored to have been used briefly in [Eastman Kodak](/source/Eastman_Kodak)'s HC-110 developer and Anchell supposes it to be a component in [Tetenal](https://en.wikipedia.org/w/index.php?title=Tetenal&action=edit&redlink=1)'s Neofin Blau developer.[22] It is a key component of Tanol from Moersch Photochemie in Germany.[23] Modern catechol developing was pioneered by noted photographer [Sandy King](https://en.wikipedia.org/w/index.php?title=Sandy_King_(photographer)&action=edit&redlink=1), whose "PyroCat" formulation is popular among modern black-and-white film photographers.[24] King's work has since inspired further 21st-century development by others such as Jay De Fehr with Hypercat and Obsidian Acqua developers, and others.[22]

## Nomenclature

Although rarely encountered, the officially "[preferred IUPAC name](/source/Preferred_IUPAC_name)" (PIN) of catechol is *benzene-1,2-diol*.[25] The trivial name *pyrocatechol* is a retained IUPAC name, according to the *1993 Recommendations for the Nomenclature of Organic Chemistry*.[26] [27]

## See also

- [Enol](/source/Enol)

- [Pyrogallol](/source/Pyrogallol)

- [Thiotimoline](/source/Thiotimoline)

## References

1. ^ [***a***](#cite_ref-iupac2013_1-0) [***b***](#cite_ref-iupac2013_1-1) "Front Matter". *Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book)*. Cambridge: [The Royal Society of Chemistry](/source/Royal_Society_of_Chemistry). 2014. p. 691. [doi](/source/Doi_(identifier)):[10.1039/9781849733069-FP001](https://doi.org/10.1039%2F9781849733069-FP001). [ISBN](/source/ISBN_(identifier)) [978-0-85404-182-4](https://en.wikipedia.org/wiki/Special:BookSources/978-0-85404-182-4).

1. ^ [***a***](#cite_ref-Ullmann_2-0) [***b***](#cite_ref-Ullmann_2-1) [***c***](#cite_ref-Ullmann_2-2) [***d***](#cite_ref-Ullmann_2-3) Fiege, Helmut; Voges, Heinz-Werner; Hamamoto, Toshikazu; Umemura, Sumio; Iwata, Tadao; Miki, Hisaya; Fujita, Yasuhiro; Buysch, Hans-Josef; Garbe, Dorothea; Paulus, Wilfried (2000), "Phenol Derivatives", *Ullmann's Encyclopedia of Industrial Chemistry*, [doi](/source/Doi_(identifier)):[10.1002/14356007.a19_313](https://doi.org/10.1002%2F14356007.a19_313), [ISBN](/source/ISBN_(identifier)) [978-3-527-30385-4](https://en.wikipedia.org/wiki/Special:BookSources/978-3-527-30385-4)

1. **[^](#cite_ref-3)** Lander, John J.; Svirbely, W. J. (1945). "The Dipole Moments of Catechol, Resorcinol and Hydroquinone". *Journal of the American Chemical Society*. **67** (2): 322–324. [Bibcode](/source/Bibcode_(identifier)):[1945JAChS..67..322L](https://ui.adsabs.harvard.edu/abs/1945JAChS..67..322L). [doi](/source/Doi_(identifier)):[10.1021/ja01218a051](https://doi.org/10.1021%2Fja01218a051).

1. ^ [***a***](#cite_ref-PGCH_4-0) [***b***](#cite_ref-PGCH_4-1) [***c***](#cite_ref-PGCH_4-2) [***d***](#cite_ref-PGCH_4-3) NIOSH Pocket Guide to Chemical Hazards. ["#0109"](https://www.cdc.gov/niosh/npg/npgd0109.html). [National Institute for Occupational Safety and Health](/source/National_Institute_for_Occupational_Safety_and_Health) (NIOSH).

1. **[^](#cite_ref-5)** Hugo Reinsch (1839) ["Einige Bemerkungen über Catechu"](http://babel.hathitrust.org/cgi/pt?id=chi.095494244;view=1up;seq=61) (Some observations about catechu), *Repertorium für die Pharmacie*, **68** : 49-58. Reinsch describes the preparation of catechol on p. 56: *"Bekanntlich wird die Katechusäure bei der Destillation zerstört, während sich ein geringer Theil davon als krystallinischer Anflug sublimirt, welcher aber noch nicht näher untersucht worden ist. Diese Säure ist vielleicht dieselbe, welche ich bei der zerstörenden Destillation des Katechus erhalten; … "* (As is well known, catechu acid is destroyed by distillation, while a small portion of it sublimates as a crystalline efflorescence, which however has still not been closely examined. This acid is perhaps the same one, which I obtained by destructive distillation of catechu; … ). On p. 58, Reinsch names the new compound: *"Die Eigenschaften dieser Säure sind so bestimmt, dass man sie füglich als eine eigenthümliche Säure betrachten und sie mit dem Namen Brenz-Katechusäure belegen kann."* (The properties of this acid are so definite, that one can regard it justifiably as a strange acid and give it the name "burned catechu acid".)

1. **[^](#cite_ref-6)** See: - H. Wackenroder (1841) ["Eigenschaften der Catechusäure"](http://babel.hathitrust.org/cgi/pt?id=mdp.39015026322258;view=1up;seq=322) (Properties of catechu acid), *Annalen der Chemie und Pharmacie*, **37** : 306-320. - Constantin Zwenger (1841) ["Ueber Catechin"](http://babel.hathitrust.org/cgi/pt?id=mdp.39015026322258;view=1up;seq=336) (On catechin), *Annalen der Chemie und Pharmacie*, **37** : 320-336. - (Anon.) (1841) ["On catechin (catechinic acid) and pyrocatechin (pyrocatechinic acid)"](https://books.google.com/books?id=Rx5DAQAAMAAJ&pg=PA194), *Philosophical Magazine*, **19** : 194-195.

1. **[^](#cite_ref-7)** See: - Rudolf Wagner (1852) ["Ueber die Farbstoffe des Gelbholzes (Morus tinctoria.)"](http://babel.hathitrust.org/cgi/pt?id=osu.32435060197167;view=1up;seq=81) (On the coloring matter of Dyer's mulberry (Morus tinctoria.)), *Journal für praktische Chemie*, **55** : 65-76. See p. 65. - August Kekulé (1867) "Ueber die Sulfosäuren des Phenols" (On the sulfonates of phenol) *Zeitschrift für Chemie*, new series, **3** : 641–646; [see p. 643.](https://archive.org/stream/zeitschriftfrch16unkngoog#page/n650/mode/2up) - Joseph Alfred Naquet, with William Cortis, trans. and Thomas Stevenson, ed., *Principles of Chemistry, founded on Modern Theories*, (London, England: Henry Renshaw, 1868), [p. 657.](https://books.google.com/books?id=maxcAAAAcAAJ&pg=PA657) See also p. 720.

1. **[^](#cite_ref-8)** See: - In 1879, the Publication Committee of the *Journal of the Chemical Society* issued instructions to its abstractors to "Distinguish all alcohols, i.e., hydroxyl-derivations of hydrocarbons, by names ending in *ol, e.g.*, quinol, catechol, … " See: Alfred H. Allen (June 20, 1879) ["Nomenclature of organic bodies,"](https://books.google.com/books?id=xrzmAAAAMAAJ&pg=PA369) *English Mechanic and World of Science*, **29** (743) : 369. - William Allen Miller, ed., *Elements of Chemistry: Theoretical and Practical, Part III: Chemistry of Carbon Compounds or Organic Chemistry, Section I …*, 5th ed. (London, England: Longmans, Green and Co., 1880), [p.524.](https://archive.org/details/elementschemist01grovgoog/page/n563)

1. **[^](#cite_ref-9)** Zheng, L. T.; Ryu, G. M.; Kwon, B. M.; Lee, W. H.; Suk, K. (2008). "Anti-inflammatory effects of catechols in lipopolysaccharide-stimulated microglia cells: Inhibition of microglial neurotoxicity". *European Journal of Pharmacology*. **588** (1): 106–13. [doi](/source/Doi_(identifier)):[10.1016/j.ejphar.2008.04.035](https://doi.org/10.1016%2Fj.ejphar.2008.04.035). [PMID](/source/PMID_(identifier)) [18499097](https://pubmed.ncbi.nlm.nih.gov/18499097).

1. ^ [***a***](#cite_ref-:0_10-0) [***b***](#cite_ref-:0_10-1) H. D. Dakin, H. T. Clarke, E. R. Taylor (1923). "Catechol". *Organic Syntheses*. **3**: 28. [doi](/source/Doi_(identifier)):[10.15227/orgsyn.003.0028](https://doi.org/10.15227%2Forgsyn.003.0028).{{[cite journal](https://en.wikipedia.org/wiki/Template:Cite_journal)}}: CS1 maint: multiple names: authors list ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_multiple_names:_authors_list))

1. **[^](#cite_ref-11)** R. S. Hanslick, W. F. Bruce, A. Mascitti (1953). "o-Phenylene Carbonate". *Org. Synth*. **33**: 74. [doi](/source/Doi_(identifier)):[10.15227/orgsyn.033.0074](https://doi.org/10.15227%2Forgsyn.033.0074).{{[cite journal](https://en.wikipedia.org/wiki/Template:Cite_journal)}}: CS1 maint: multiple names: authors list ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_multiple_names:_authors_list))

1. **[^](#cite_ref-12)** Anderson, Bryan F.; Buckingham, David A.; Robertson, Glen B.; Webb, John; Murray, Keith S.; Clark, Paul E. (1976). ["Models for the bacterial iron-transport chelate enterochelin"](/source/Enterochelin). *Nature*. **262** (5570): 722–724. [Bibcode](/source/Bibcode_(identifier)):[1976Natur.262..722A](https://ui.adsabs.harvard.edu/abs/1976Natur.262..722A). [doi](/source/Doi_(identifier)):[10.1038/262722a0](https://doi.org/10.1038%2F262722a0). [PMID](/source/PMID_(identifier)) [134287](https://pubmed.ncbi.nlm.nih.gov/134287). [S2CID](/source/S2CID_(identifier)) [3045676](https://api.semanticscholar.org/CorpusID:3045676).

1. **[^](#cite_ref-13)** Schweigert, Nina; [Zehnder, Alexander J. B.](/source/Alexander_Zehnder); Eggen, Rik I. L. (2001). "Chemical properties of catechols and their molecular modes of toxic action in cells, from microorganisms to mammals. Minireview". *Environmental Microbiology*. **3** (2): 81–91. [doi](/source/Doi_(identifier)):[10.1046/j.1462-2920.2001.00176.x](https://doi.org/10.1046%2Fj.1462-2920.2001.00176.x). [PMID](/source/PMID_(identifier)) [11321547](https://pubmed.ncbi.nlm.nih.gov/11321547).

1. **[^](#cite_ref-14)** Griffith, W. P. (1993). "Recent Advances in Dioxolene Chemistry". *Transition Metal Chemistry*. **18** (2): 250–256. [doi](/source/Doi_(identifier)):[10.1007/BF00139966](https://doi.org/10.1007%2FBF00139966). [S2CID](/source/S2CID_(identifier)) [93790780](https://api.semanticscholar.org/CorpusID:93790780).

1. **[^](#cite_ref-pmid19300498_15-0)** [PDB](/source/Protein_Data_Bank): [2ZI8](https://www.rcsb.org/structure/2ZI8)​; Yam KC, D'Angelo I, Kalscheuer R, Zhu H, Wang JX, Snieckus V, Ly LH, Converse PJ, Jacobs WR, Strynadka N, Eltis LD (March 2009). ["Studies of a ring-cleaving dioxygenase illuminate the role of cholesterol metabolism in the pathogenesis of Mycobacterium tuberculosis"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2652662). *PLOS Pathog*. **5** (3) e1000344. [doi](/source/Doi_(identifier)):[10.1371/journal.ppat.1000344](https://doi.org/10.1371%2Fjournal.ppat.1000344). [PMC](/source/PMC_(identifier)) [2652662](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2652662). [PMID](/source/PMID_(identifier)) [19300498](https://pubmed.ncbi.nlm.nih.gov/19300498).

1. **[^](#cite_ref-16)** Bolton, Judy L.; Dunlap, Tareisha L.; Dietz, Birgit M. (2018). ["Formation and Biological Targets of Botanical o-Quinones"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6643002). *Food and Chemical Toxicology*. **120**: 700–707. [doi](/source/Doi_(identifier)):[10.1016/j.fct.2018.07.050](https://doi.org/10.1016%2Fj.fct.2018.07.050). [PMC](/source/PMC_(identifier)) [6643002](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6643002). [PMID](/source/PMID_(identifier)) [30063944](https://pubmed.ncbi.nlm.nih.gov/30063944). [S2CID](/source/S2CID_(identifier)) [51887182](https://api.semanticscholar.org/CorpusID:51887182).

1. **[^](#cite_ref-17)** Briggs DEG (1999). ["Molecular taphonomy of animal and plant cuticles: selective preservation and diagenesis"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1692454). *Philosophical Transactions of the Royal Society B: Biological Sciences*. **354** (1379): 7–17. [doi](/source/Doi_(identifier)):[10.1098/rstb.1999.0356](https://doi.org/10.1098%2Frstb.1999.0356). [PMC](/source/PMC_(identifier)) [1692454](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1692454).

1. **[^](#cite_ref-18)** *Encyclopedia of Reagents for Organic Synthesis*, 2001, [doi](/source/Doi_(identifier)):[10.1002/047084289X](https://doi.org/10.1002%2F047084289X), [hdl](/source/Hdl_(identifier)):[10261/236866](https://hdl.handle.net/10261%2F236866), [ISBN](/source/ISBN_(identifier)) [978-0-471-93623-7](https://en.wikipedia.org/wiki/Special:BookSources/978-0-471-93623-7)

1. **[^](#cite_ref-19)** Fahlbusch, Karl-Georg; Hammerschmidt, Franz-Josef; Panten, Johannes; Pickenhagen, Wilhelm; Schatkowski, Dietmar; Bauer, Kurt; Garbe, Dorothea; Surburg, Horst (2003), "Flavors and Fragrances", *Ullmann's Encyclopedia of Industrial Chemistry*, [doi](/source/Doi_(identifier)):[10.1002/14356007.a11_141](https://doi.org/10.1002%2F14356007.a11_141), [ISBN](/source/ISBN_(identifier)) [978-3-527-30385-4](https://en.wikipedia.org/wiki/Special:BookSources/978-3-527-30385-4)

1. **[^](#cite_ref-20)** Eder, Josef Maria (January 1880). "Ueber die chemische Zusammensetzung des Pyroxylins und die Formel der Cellulose" [About the chemical composition of pyroxylin and the formula of cellulose]. *Berichte der deutschen chemischen Gesellschaft* [*Reports of the German Chemical Society*] (in German). **13** (1): 169–186. [doi](/source/Doi_(identifier)):[10.1002/cber.18800130151](https://doi.org/10.1002%2Fcber.18800130151). [ISSN](/source/ISSN_(identifier)) [0365-9496](https://search.worldcat.org/issn/0365-9496).

1. **[^](#cite_ref-21)** Eder, Josef Maria (1880). *Der neue Eisenoxalat-Entwickler: und dessen Vergleichung mit dem Pyrogallus-Entwickler* [*The new iron oxalate developer: and its comparison with the Pyrogallol developer*] (in German). Vienna: Verlag der Photographischen Correspondenz: Hermann Vogel. [OCLC](/source/OCLC_(identifier)) [80152687](https://search.worldcat.org/oclc/80152687).{{[cite book](https://en.wikipedia.org/wiki/Template:Cite_book)}}: CS1 maint: publisher location ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_publisher_location))

1. ^ [***a***](#cite_ref-Stephen_G._Anchell_22-0) [***b***](#cite_ref-Stephen_G._Anchell_22-1) Stephen G. Anchell (2012-09-10). *The Darkroom Cookbook*. Taylor & Francis. [ISBN](/source/ISBN_(identifier)) [978-1-136-09277-0](https://en.wikipedia.org/wiki/Special:BookSources/978-1-136-09277-0).

1. **[^](#cite_ref-23)** Wolfgang, Moersch (13 January 2025). ["TANOL-AB-EN.pdf"](https://www.moersch-photochemie.de/wp-content/uploads/2025/03/TANOL-AB-EN-.pdf#page=3) (PDF). *Moersch Photochemie*. Retrieved 2 January 2026.{{[cite web](https://en.wikipedia.org/wiki/Template:Cite_web)}}: CS1 maint: url-status ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_url-status))

1. **[^](#cite_ref-24)** Stephen G. Anchell; Bill Troop (1998). *The Film Developing Cookbook*. [ISBN](/source/ISBN_(identifier)) [978-0-240-80277-0](https://en.wikipedia.org/wiki/Special:BookSources/978-0-240-80277-0).

1. **[^](#cite_ref-25)** [Preferred IUPAC Names](http://old.iupac.org/reports/provisional/abstract04/BB-prs310305/Chapter6-Sec60-64.pdf). September 2004, Chapter 6, Sect 60–64, p. 38

1. **[^](#cite_ref-26)** IUPAC, Commission on Nomenclature of Organic Chemistry. A Guide to IUPAC Nomenclature of Organic Compounds (Recommendations 1993) [R-5.5.1.1 Alcohols and phenols.](http://www.acdlabs.com/iupac/nomenclature/93/r93_414.htm)

1. **[^](#cite_ref-27)** Panico, R.; Powell, W. H., eds. (1994). *A Guide to IUPAC Nomenclature of Organic Compounds 1993*. Oxford: Blackwell Science. [ISBN](/source/ISBN_(identifier)) [978-0-632-03488-8](https://en.wikipedia.org/wiki/Special:BookSources/978-0-632-03488-8).

This article incorporates text from a publication now in the [public domain](/source/Public_domain): [Chisholm, Hugh](/source/Hugh_Chisholm), ed. (1911). "[Catechu](https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica/Catechu)". *[Encyclopædia Britannica](/source/Encyclop%C3%A6dia_Britannica_Eleventh_Edition)* (11th ed.). Cambridge University Press.

## External links

Wikimedia Commons has media related to [Pyrocatechol](https://commons.wikimedia.org/wiki/Category:Pyrocatechol).

- [International Chemical Safety Card 0411](http://www.inchem.org/documents/icsc/icsc/eics0411.htm)

- [NIOSH Pocket Guide to Chemical Hazards](https://www.cdc.gov/niosh/npg/npgd0109.html)

- [IARC Monograph: "Catechol"](https://web.archive.org/web/20051012222358/http://www-cie.iarc.fr/htdocs/monographs/vol71/012-catechol.html)

- [IUPAC Nomenclature of Organic Chemistry](http://www.acdlabs.com/iupac/nomenclature/) (online version of the "*Blue Book*")

Authority control databases National United States Israel Other Yale LUX

---
Adapted from the Wikipedia article [Catechol](https://en.wikipedia.org/wiki/Catechol) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Catechol?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.