Catechol

Catechol
Pyrocatechol	Ball-and-stick model
Names
	Preferred IUPAC name Benzene-1,2-diol
	Other names Pyrocatechol; 1,2-Benzenediol; 2-Hydroxyphenol; 1,2-Dihydroxybenzene; o-Benzenediol; o-Dihydroxybenzene
Identifiers
CAS Number	120-80-9 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	471401
ChEBI	CHEBI:18135 ;
ChEMBL	ChEMBL280998 ;
ChemSpider	13837760 ;
DrugBank	DB02232;
ECHA InfoCard	100.004.025
EC Number	204-427-5;
Gmelin Reference	2936
KEGG	C00090 ;
PubChem CID	289;
RTECS number	UX1050000;
UNII	LF3AJ089DQ ;
CompTox Dashboard (EPA)	DTXSID3020257 ;
	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
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
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%–?
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	300 mg/kg (rat, oral)
	NIOSH (US health exposure limits):
PEL (Permissible)	none
REL (Recommended)	TWA 5 ppm (20 mg/m3) [skin]
IDLH (Immediate danger)	N.D.
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). verify (what is ?) Infobox references

Catechol (/ˈkætɪtʃɒl/ or /ˈkætɪkɒl/), also known as pyrocatechol or 1,2-dihydroxybenzene, is an organic compound with the molecular formula C₆H₄(OH)₂. It is the ortho isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amounts. It was first discovered by destructive distillation of the plant extract 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 and vegetables.^[2]

^ ^a ^b "Front Matter". Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 691. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
^ ^a ^b Cite error: The named reference Ullmann was invoked but never defined (see the help page).
^ 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. doi:10.1021/ja01218a051.
^ ^a ^b ^c ^d NIOSH Pocket Guide to Chemical Hazards. "#0109". National Institute for Occupational Safety and Health (NIOSH).

[iupac2013-1] "Front Matter". Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 691. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.

[Ullmann-2] Cite error: The named reference Ullmann was invoked but never defined (see the help page).

[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. doi:10.1021/ja01218a051.

[PGCH-4] NIOSH Pocket Guide to Chemical Hazards. "#0109". National Institute for Occupational Safety and Health (NIOSH).

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