View source for Phenol

{{short description|Organic compound (C6H5OH)}}
{{About|the molecule|the group of chemicals that contains a phenol group|Phenols}}
{{Redirect-distinguish|Carbolic acid|carbonic acid|carboxylic acid}}
{{Chembox
| Watchedfields  = changed
| verifiedrevid  = 464200484
| Name           = Phenol
| ImageFile      = 
| ImageFileL1    = Phenol2.svg
| ImageClassL1   = skin-invert-image
| ImageSizeL1    = 80px
| ImageFileR1    = Phenol-2.svg
| ImageClassR1   = skin-invert-image
| ImageSizeR1    = 84px
| ImageFileL2    = Phenol-3D-balls.png
| ImageClassL2   = bg-transparent
| ImageFileR2    = Phenol-3D-vdW.png
| ImageClassR2   = bg-transparent
| ImageFile3     = Phenol 2 grams.jpg
| PIN            = Phenol<ref name=iupac2013>{{cite book |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book) |publisher=[[Royal Society of Chemistry|The Royal Society of Chemistry]] |date=2014 |location=Cambridge |page=690 |doi=10.1039/9781849733069-FP001 |isbn=978-0-85404-182-4 |quote=Only one name is retained, phenol, for C<sub>6</sub>H<sub>5</sub>-OH, both as a preferred name and for general nomenclature.| chapter=Front Matter}}</ref>
| SystematicName = Benzenol
| OtherNames     = {{ubl|Carbolic acid|Phenolic acid|Phenylic acid|Hydroxybenzene|Phenic acid|Phenyl alcohol|Phenyl hydroxide}}
| IUPACName      = 
| Section1       = {{Chembox Identifiers
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 15882
| DrugBank_Ref = {{drugbankcite|correct|drugbank}}
| DrugBank = DB03255
| SMILES = Oc1ccccc1
| PubChem = 996
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 14060
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C6H6O/c7-6-4-2-1-3-5-6/h1-5,7H
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = ISWSIDIOOBJBQZ-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 108-95-2
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 971
| RTECS = SJ3325000
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 339NCG44TV
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = D00033
| InChI=1/C6H6O/c7-6-4-2-1-3-5-6/h1-5,7H
| UNNumber = 2821 (solution)<br />2312 (molten)<br />1671 (solid)
  }}
| Section2       = {{Chembox Properties
| C=6 | H=6 | O=1
| MolarMassUnit = g/mol
| Appearance = Transparent crystalline solid
| Odor = Sweet and tarry
| Density = 1.07{{nbsp}}g/cm<sup>3</sup>
| Solubility = 8.3{{nbsp}}g/100{{nnbsp}}mL (20{{nbsp}}°C)
| MeltingPtC = 40.5
| BoilingPtC = 181.7
| ConjugateBase = Phenoxide
| pKa = {{ubl
 | 9.95 (in water),
 | 18.0 (in DMSO),
 | 29.1 (in acetonitrile)<ref>{{cite journal|doi=10.1021/jo702513w|title=Pentakis(trifluoromethyl)phenyl, a Sterically Crowded and Electron-withdrawing Group: Synthesis and Acidity of Pentakis(trifluoromethyl)benzene, -toluene, -phenol, and -aniline|year=2008|last1=Kütt|first1=Agnes|last2=Movchun|first2=Valeria|last3=Rodima|first3=Toomas|last4=Dansauer|first4=Timo|last5=Rusanov|first5=Eduard B.|last6=Leito|first6=Ivo|last7=Kaljurand|first7=Ivari|last8=Koppel|first8=Juta|last9=Pihl|first9=Viljar|last10=Koppel|first10=Ivar|last11=Ovsjannikov|first11=Gea|last12=Toom|first12=Lauri|last13=Mishima|first13=Masaaki|last14=Medebielle|first14=Maurice|last15=Lork|first15=Enno|last16=Röschenthaler|first16=Gerd-Volker|last17=Koppel|first17=Ilmar A.|last18=Kolomeitsev|first18=Alexander A.|journal=The Journal of Organic Chemistry|volume=73|issue=7|pages=2607–20|pmid=18324831|url=https://figshare.com/articles/Pentakis_trifluoromethyl_phenyl_a_Sterically_Crowded_and_Electron_withdrawing_Group_Synthesis_and_Acidity_of_Pentakis_trifluoromethyl_benzene_toluene_phenol_and_aniline/2946736 |display-authors=3}}</ref>
 }}
| Dipole = 1.224{{nbsp}}[[Debye|D]]
| LambdaMax = 270.75{{nbsp}}nm<ref name=pubchem/>
| VaporPressure = 0.4{{nbsp}}mmHg (20{{nbsp}}°C)<ref name=PGCH/>
| LogP = 1.48<ref name="chemsrc">{{cite web|url=https://www.chemsrc.com/en/cas/108-95-2_1101388.html|title=Phenol_msds}}</ref>
  }}
| Section3       = 
| Section4       = 
| Section5       = 
| Section6       = {{Chembox Pharmacology
| ATCCode_prefix = C05
| ATCCode_suffix = BB05
| ATC_Supplemental = {{ATC|D08|AE03}}, {{ATC|N01|BX03}}, {{ATC|R02|AA19}}
}}
| Section7       = {{Chembox Hazards
| GHSPictograms = {{GHS05}}{{GHS06}}{{GHS08}}<ref name="sigma">{{Sigma-Aldrich|sial|id=77608|name=Phenol|accessdate=2022-02-15}}</ref>
| HPhrases = {{H-phrases|301|311|314|331|341|373}}<ref name="sigma"/>
| PPhrases = {{P-phrases|261|280|301+310|305+351+338|310}}<ref name="sigma"/>
| GHSSignalWord = Danger
| NFPA-H = 3
| NFPA-F = 2
| NFPA-R =0
| NFPA-S =
| FlashPtC = 79
| ExternalSDS=[https://www.chemblink.com/MSDS/MSDSFiles/108-95-2_Sigma-Aldrich.pdf]
| PEL = TWA 5{{nbsp}}ppm (19{{nbsp}}mg/m<sup>3</sup>) [skin]<ref name=PGCH>{{PGCH|0493}}</ref>
| ExploLimits = 1.8–8.6%<ref name=PGCH/>
| IDLH = 250{{nbsp}}ppm<ref name=PGCH/>
| LC50 = {{ubl
 | 19{{nbsp}}ppm (mammal)
 | 81{{nbsp}}ppm (rat)
 | 69{{nbsp}}ppm (mouse)<ref name=IDLH>{{IDLH|108952|Phenol}}</ref>
 }}
| LD50 = {{ubl
 | 317{{nbsp}}mg/kg (rat, oral)
 | 270{{nbsp}}mg/kg (mouse, oral)<ref name=IDLH/>
 }}
| REL = {{ubl
 | TWA 5{{nbsp}}ppm (19{{nbsp}}mg/m<sup>3</sup>)
 | C 15.6{{nbsp}}ppm (60{{nbsp}}mg/m<sup>3</sup>) [15-minute] [skin]<ref name=PGCH/>
 }}
| LDLo = {{ubl
 | 420{{nbsp}}mg/kg (rabbit, oral)
 | 500{{nbsp}}mg/kg (dog, oral)
 | 80{{nbsp}}mg/kg (cat, oral)<ref name=IDLH/>
 }}
  }}
| Section8       = {{Chembox Related
| OtherCompounds = {{ubl|[[Thiophenol]]|[[Sodium phenoxide]]}}
  }}
}}
'''Phenol''' (also known as '''carbolic acid''', '''phenolic acid''', or '''benzenol''') is an [[aromaticity|aromatic]] [[organic compound]] with the molecular [[chemical formula|formula]] {{chem2|C6H5OH}}.<ref name="pubchem">{{cite web |title=Phenol |url=https://pubchem.ncbi.nlm.nih.gov/compound/996 |publisher=PubChem, US National Library of Medicine |access-date=9 June 2025 |date=7 June 2025}}</ref><ref name="cdc">{{cite web |title=Medical Management Guidelines for Phenol|url=https://wwwn.cdc.gov/TSP/MMG/MMGDetails.aspx?mmgid=144&toxid=27 |publisher=National Institute for Occupational Safety and Health, US Centers for Disease Control and Prevention |access-date=24 June 2025 |date=21 October 2014}}</ref> It is a white [[crystal]]line [[solid]] that is [[volatility (chemistry)|volatile]] and can catch fire.<ref name=pubchem/> 

The molecule consists of a [[phenyl group]] ({{chem2|\sC6H5}}) bonded to a [[hydroxy group]] ({{chem2|\sOH}}). Mildly [[acidic]], it requires careful handling because it can cause [[chemical burn]]s.<ref name=pubchem/> It is acutely [[Toxicity|toxic]] and is considered a health [[hazard]].<ref name=pubchem/><ref name=cdc/>

Phenol was first extracted from [[coal tar]], but today is produced on a large scale (about 7 million tonnes a year) from [[petroleum]]-derived feedstocks. It is an important industrial [[commodity]] as a [[precursor (chemistry)|precursor]] to many materials and useful compounds, and is a liquid when manufactured.<ref name=pubchem/><ref name="Ullmann">{{Ullmann|doi=10.1002/14356007.a19_299.pub3 |title=Phenol|year=2004|last1=Weber|first1=Manfred|last2=Weber|first2=Markus|last3=Kleine-Boymann|first3=Michael}}</ref> It is primarily used to synthesize [[plastics]] and related materials.<ref name=cdc/> Phenol and its chemical [[derivative (chemistry)|derivatives]] are essential for production of [[polycarbonate]]s, [[epoxy|epoxies]], [[Explosive|explosives]] such as [[picric acid]], [[Bakelite]], [[nylon]], [[detergent]]s, [[herbicide]]s such as [[phenoxy herbicide]]s, and numerous [[pharmaceutical drug]]s.<ref>{{cite book|title=The Chemistry of Phenols|editor=Zvi Rappoport |series = PATAI'S Chemistry of Functional Groups |isbn=978-0-470-85727-4 |doi=10.1002/0470857277|year=2003 |publisher=John Wiley & Sons}}</ref> 

==Properties==
Phenol is an organic compound appreciably [[solubility|soluble]] in water, with about 84.2&nbsp;g dissolving in 1000&nbsp;ml (0.895 [[Molar concentration|M]]). Homogeneous mixtures of phenol and water at phenol to water mass ratios of ~2.6 and higher are possible. The sodium salt of phenol, [[sodium phenoxide]], is far more water-soluble. It is a combustible solid (NFPA rating = 2). When heated, phenol produces flammable vapors that are explosive at concentrations of 3 to 10% in air. Carbon dioxide or dry chemical extinguishers should be used to fight phenol fires.<ref name=pubchem/>

===Acidity===
Phenol is a weak acid, with a pH range of 5 to 6. In aqueous solution in the pH range ca. 8–12 it is in equilibrium with the '''phenolate''' [[anion]] {{chem2|C6H5O-}} (also called '''phenoxide''' or '''carbolate'''):<ref>{{March6th}}</ref>
:{{chem2 | C6H5OH <-> C6H5O- + H+ }}

:[[File:Phenol-phenolate equilibrium.svg|class=skin-invert-image|thumb|left|upright=1.5|[[Resonance structures]] of the phenoxide anion]]{{clear-left}}

Phenol is more acidic than [[Aliphatic compounds|aliphatic]] alcohols. Its enhanced acidity is attributed to [[resonance stabilization]] of [[phenolate]] anion. In this way, the negative charge on oxygen is delocalized on to the [[arene substitution patterns|ortho and para]] carbon atoms through the pi system.<ref>''Organic Chemistry'' 2nd Ed. John McMurry {{ISBN|0-534-07968-7}}</ref> An alternative explanation involves the sigma framework, postulating that the dominant effect is the [[inductive effect|induction]] from the more electronegative [[orbital hybridisation|sp<sup>2</sup> hybridised carbons]]; the comparatively more powerful inductive withdrawal of electron density that is provided by the sp<sup>2</sup> system compared to an sp<sup>3</sup> system allows for great stabilization of the oxyanion. In support of the second explanation, the [[acid dissociation constant|p''K''<sub>a</sub>]] of the [[enol]] of [[acetone]] in water is 10.9, making it only slightly less acidic than phenol (p''K''<sub>a</sub> 10.0).<ref name=pubchem/> Thus, the greater number of resonance structures available to phenoxide compared to acetone enolate seems to contribute little to its stabilization. However, the situation changes when solvation effects are excluded.

====Hydrogen bonding====
In [[carbon tetrachloride]] and in alkane solvents, phenol [[hydrogen bonds]] with a wide range of [[Lewis acids and bases|Lewis bases]] such as [[pyridine]], [[diethyl ether]], and [[diethyl sulfide]].  The enthalpies of adduct formation and the {{chem2|\sOH}} IR frequency shifts accompanying adduct formation have been compiled.<ref>Drago, R S. Physical Methods For Chemists, (Saunders College Publishing 1992), ISBN 0-03-075176-4</ref>  Phenol is classified as a [[HSAB theory|hard acid]].<ref>Laurence, C. and Gal, J-F.  Lewis Basicity and Affinity Scales, Data and Measurement, (Wiley 2010) pp 50-51 ISBN 978-0-470-74957-9</ref><ref>{{cite journal|author1=Cramer, R. E. |author2=Bopp, T. T. |year=1977|title= Graphical display of the enthalpies of adduct formation for Lewis acids and bases |journal= Journal of Chemical Education |volume=54|pages=612–613|doi= 10.1021/ed054p612}} The plots shown in this paper used older parameters. Improved E&C parameters are listed in [[ECW model]].</ref>

====Tautomerism====
[[File:Phenol tautomers.svg|class=skin-invert-image|left|thumb|upright=.75|Phenol-cyclohexadienone tautomerism]]
Phenol exhibits [[keto-enol tautomerism]] with its unstable keto tautomer cyclohexadienone, but the effect is nearly negligible. The equilibrium constant for enolisation is approximately 10<sup>−13</sup>, which means only one in every ten trillion molecules is in the keto form at any moment.<ref>{{cite journal |title=Ketonization equilibria of phenol in aqueous solution |first1=Marco |last1=Capponi |first2=Ivo G. |last2=Gut |first3=Bruno |last3=Hellrung |first4=Gaby |last4=Persy |first5=Jakob |last5=Wirz |journal=[[Canadian Journal of Chemistry|Can. J. Chem.]] |year=1999 |volume=77 |pages=605–613 |doi=10.1139/cjc-77-5-6-605 |issue=5–6}}</ref> The small amount of stabilisation gained by exchanging a C=C bond for a C=O bond is more than offset by the large destabilisation resulting from the loss of aromaticity. Phenol therefore exists essentially entirely in the enol form.<ref>{{Clayden|page=531}}</ref> 4,4' Substituted cyclohexadienone can undergo a [[dienone–phenol rearrangement]] in acid conditions and form stable 3,4‐disubstituted phenol.<ref>{{cite journal |last1=Arnold |first1=Richard T. |last2=Buckley |first2=Jay S. |title=The Dienone-Phenol Rearrangement. II. Rearrangement of 1-Keto-4-methyl-4-phenyl-1,4-dihydronaphthalene |journal=J. Am. Chem. Soc. |date=1 May 1949 |volume=71 |issue=5 |page=1781 |doi=10.1021/ja01173a071|bibcode=1949JAChS..71.1781A }}</ref>

For substituted phenols, several factors can favor the keto tautomer: (a) additional hydroxy groups (see [[resorcinol]]) (b) annulation as in the formation of [[naphthol]]s, and (c) deprotonation to give the phenolate.<ref>{{cite book|title=The Chemistry of Phenols|editor=Zvi Rappoport |series = PATAI'S Chemistry of Functional Groups | chapter=Tautomeric Equilibria and Rearrangements Involving Phenols |doi=10.1002/0470857277.ch11
| year=2003 |publisher=John Wiley & Sons| author=Sergei M. Lukyanov, Alla V. Koblik|pages=713–838 |isbn=0-471-49737-1 }}</ref>

Phenoxides are [[enolate]]s stabilised by [[aromaticity]]. Under normal circumstances, phenoxide is more reactive at the oxygen position, but the oxygen position is a "hard" nucleophile whereas the alpha-carbon positions tend to be "soft".<ref>{{cite journal |title=2,6,6-Trimethyl-2,4-Cyclohexadione |author1=David Y. Curtin |author2=Allan R. Stein |name-list-style=amp |journal=[[Organic Syntheses]] |year=1966 |volume=46 |page=115 |url=http://www.orgsyn.org/orgsyn/prep.asp?prep=cv5p1092 |doi=10.15227/orgsyn.046.0115 |access-date=2010-03-31 |archive-url=https://web.archive.org/web/20110605132001/http://www.orgsyn.org/orgsyn/prep.asp?prep=cv5p1092 |archive-date=2011-06-05 |url-access=subscription }}</ref>

===Reactions===
[[File:Hockpart2.svg|class=skin-invert-image|thumb|right|The Hock process leading to phenol via [[autoxidation]] of cumene.]]
[[File:Phenol-elpot-3D-vdW.png|right|thumb|[[Polar surface area]] of a "neutral" phenol substructure "shape". An image of a computed electrostatic surface of neutral phenol molecule, showing neutral regions in green, electronegative areas in orange-red, and the electropositive phenolic proton in blue.]]
[[File:Phenol in water.PNG|class=skin-invert-image|thumb|right|Phenol water phase diagram: Certain combinations of phenol and water can make two solutions in one bottle.]]

Phenol is highly reactive toward [[electrophilic aromatic substitution]]. The enhanced nucleophilicity is attributed to donation [[pi electron]] density from O into the ring. Many groups can be attached to the ring, via [[halogenation]], [[acylation]], [[sulfonation]], and related processes. 

Phenol is so strongly activated that bromination and chlorination lead readily to polysubstitution.<ref>{{Ullmann|vauthors=Muller F,  Caillard L |title=Chlorophenols|year=2011|doi=10.1002/14356007.a07_001.pub2}}</ref> The reaction affords 2- and 4-substituted derivatives. The regiochemistry of halogenation changes in strongly acidic solutions where {{chem2|PhOH2]+}} predominates. Phenol reacts with dilute nitric acid at room temperature to give a mixture of 2-nitrophenol and 4-nitrophenol while with concentrated nitric acid, additional nitro groups are introduced, e.g. to give [[Picric acid|2,4,6-trinitrophenol]].  [[Friedel Crafts alkylation]]s of phenol and its derivatives often proceed without catalysts.  Alkylating agents include alkyl halides, alkenes, and ketones.  Thus, [[1-Bromoadamantane|adamantyl-1-bromide]], [[dicyclopentadiene]]), and [[cyclohexanone]]s give respectively 4-adamantylphenol, a bis(2-hydroxyphenyl) derivative, and a 4-cyclohexylphenols.  [[Alcohol (chemistry)|Alcohol]]s and [[hydroperoxide]]s alkylate phenols in the presence of [[solid acid]] [[catalyst]]s (e.g. certain [[zeolite]]).  [[Cresol]]s and cumyl phenols can be produced in that way.<ref name=reddy>{{cite book|title=The Chemistry of Phenols|editor=Zvi Rappoport |series = PATAI'S Chemistry of Functional Groups | chapter=Electrophilic reactions of phenols |doi=10.1002/0470857277.ch9|year=2003 |publisher =John Wiley & Sons|author=V. Prakash Reddy. G. K. Surya Prakash|pages=605–660 |isbn=0-471-49737-1 }}</ref>

Aqueous solutions of phenol are weakly acidic and turn blue litmus slightly to red. Phenol is neutralized by [[sodium hydroxide]] forming sodium phenate or phenolate, but being weaker than [[carbonic acid]], it cannot be neutralized by [[sodium bicarbonate]] or [[sodium carbonate]] to liberate [[carbon dioxide]].
:{{chem2|C6H5OH + NaOH -> C6H5ONa + H2O}}

When a mixture of phenol and [[benzoyl chloride]] are shaken in presence of dilute [[sodium hydroxide]] solution, [[phenyl benzoate]] is formed. This is an example of the [[Schotten–Baumann reaction]]:
:{{chem2|C6H5COCl  + HOC6H5 -> C6H5CO2C6H5 + HCl}}

Phenol is reduced to [[benzene]] when it is distilled with [[zinc]] dust or when its vapour is passed over granules of zinc at 400&nbsp;°C:<ref>{{cite book|last=Roscoe|first=Henry|title=A treatise on chemistry, Volume 3, Part 3|year=1891|publisher=Macmillan & Co.|location=London|page=23|url=https://books.google.com/books?id=HEY9AAAAYAAJ&q=zinc&pg=PA199}}</ref>
:{{chem2|C6H5OH + Zn -> C6H6 + ZnO}}

When phenol is treated with [[diazomethane]] in the presence of [[boron trifluoride]] ({{chem2|BF3}}), [[anisole]] is obtained as the main product and nitrogen gas as a byproduct.
:{{chem2|C6H5OH + CH2N2 -> C6H5OCH3 + N2}}

Phenol and its derivatives react with iron(III) chloride to give intensely colored solutions containing phenoxide complexes.

==Production==
Because of phenol's commercial importance, many methods have been developed for its production, but the cumene process is the dominant technology. 

===Cumene process===

Accounting for 95% of production (2003) is the [[cumene process]], also called ''Hock process''. It  involves the partial [[redox|oxidation]] of [[cumene]] (isopropylbenzene) via the [[Hock rearrangement]]:<ref name="Ullmann"/> Compared to most other processes, the cumene process uses mild conditions and inexpensive raw materials. For the process to be economical, both phenol and the acetone by-product must be in demand.<ref name="essential chemical">{{cite web |url=http://www.essentialchemicalindustry.org/chemicals/phenol.html |title=Phenol -- The essential chemical industry online |date=2017-01-11 |access-date=2018-01-02}}</ref><ref name="chemistry.org"/> In 2010, worldwide demand for acetone was approximately 6.7 million tonnes, 83 percent of which was satisfied with acetone produced by the cumene process.

A route analogous to the cumene process begins with [[cyclohexylbenzene]]. It is [[oxidized]] to a [[hydroperoxide]], akin to the production of [[cumene hydroperoxide]]. Via the Hock rearrangement, cyclohexylbenzene hydroperoxide cleaves to give phenol and [[cyclohexanone]]. Cyclohexanone is an important precursor to some [[nylon]]s.<ref name="acs phenol">{{cite web |url=https://www.acs.org/content/acs/en/pressroom/cutting-edge-chemistry/what-s-new-in-phenol-production-.html |title=What's New in Phenol Production? |last=Plotkin |first=Jeffrey S. |publisher=American Chemical Society |date=2016-03-21 |access-date=2018-01-02 |archive-url=https://web.archive.org/web/20191027122212/https://www.acs.org/content/acs/en/pressroom/cutting-edge-chemistry/what-s-new-in-phenol-production-.html |archive-date=2019-10-27 }}</ref>

===Oxidation of benzene, toluene, cyclohexylbenzene===
The direct oxidation of [[benzene]] ({{chem2|C6H6}}) to phenol is possible, but it has not been commercialized: 
:{{chem2|C6H6 + O -> C6H5OH}}
[[Nitrous oxide]] is a potentially "green" oxidant that is a more potent oxidant than O<sub>2</sub>. Routes for the generation of nitrous oxide however remain uncompetitive.<ref name=CatalysisToday2005>{{cite journal |last1=Parmon |first1=V. N. |last2=Panov |first2=G. I. |last3=Uriarte |first3=A. |last4=Noskov |first4=A. S. |title=Nitrous oxide in oxidation chemistry and catalysis application and production |journal=Catalysis Today |volume=100 |issue=2005 |pages=115–131 |doi=10.1016/j.cattod.2004.12.012 |year=2005}}</ref><ref name="essential chemical"/><ref name="acs phenol"/>

An [[electrosynthesis]] employing [[alternating current]] gives phenol from benzene.<ref>{{cite journal |last1=Lee |first1=Byungik |last2=Naito |first2=Hiroto |last3=Nagao |first3=Masahiro |last4=Hibino |first4=Takashi |title=Alternating-Current Electrolysis for the Production of Phenol from Benzene |journal=Angewandte Chemie International Edition |date=9 July 2012 |volume=51 |issue=28 |pages=6961–6965 |doi=10.1002/anie.201202159|pmid=22684819}}</ref>

The oxidation of [[toluene]], as developed by [[Dow Chemical]], involves copper-catalyzed reaction of molten sodium benzoate with air:
:{{chem2|C6H5CH3 + 2 O2 -> C6H5OH + CO2 + H2O}}
The reaction is proposed to proceed via formation of benzyoylsalicylate.<ref name="Ullmann"/>

[[Autoxidation]] of [[cyclohexylbenzene]] gives the [[hydroperoxide]]. Decomposition of this hydroperoxide affords [[cyclohexanone]] and phenol.<ref name="Ullmann"/>

===Older methods===
Early methods relied on extraction of phenol from coal derivatives or the hydrolysis of benzene derivatives.

====Hydrolysis of benzenesulfonic acid====
The original commercial route was developed by [[Bayer]] and [[Monsanto]] in the early 1900s, based on discoveries by [[Charles Adolphe Wurtz|Wurtz]] and [[August Kekulé|Kekulé]].  The method involves the reaction of a strong base with [[benzenesulfonate|benzenesulfonic acid]], proceeded by the reaction of hydroxide with [[sodium benzenesulfonate]] to give sodium phenoxide. Acidification of the latter gives phenol. The net conversion is:<ref name="Wittcoff">Wittcoff, H.A., Reuben, B.G. Industrial Organic Chemicals in Perspective. Part One: Raw Materials and Manufacture. Wiley-Interscience, New York. 1980.</ref>
:{{chem2|C6H5SO3H + 2 NaOH -> C6H5OH + Na2SO3 + H2O}}

====Hydrolysis of chlorobenzene====
[[Chlorobenzene]] can be hydrolyzed to phenol using a base ([[Dow process (phenol)|Dow process]]) or steam ([[Raschig–Hooker process]]):<ref name="chemistry.org">{{cite web |url=http://www.chemistry.org/portal/a/c/s/1/feature_pro.html?id=c373e908e6e847ac8f6a17245d830100 |title=Direct Routes to Phenol |access-date=2007-04-09 |archive-url=https://web.archive.org/web/20070409042033/http://www.chemistry.org/portal/a/c/s/1/feature_pro.html?id=c373e908e6e847ac8f6a17245d830100 |archive-date=2007-04-09 }}</ref><ref name="acs phenol"/><ref name="Franck"/>
:{{chem2|C6H5Cl + NaOH -> C6H5OH + NaCl}}
:{{chem2|C6H5Cl + H2O -> C6H5OH + HCl}}
These methods suffer from the cost of the chlorobenzene and the need to dispose of the chloride byproduct.

====Coal pyrolysis====
Phenol is also a recoverable byproduct of [[coal]] pyrolysis.<ref name="Franck">Franck, H.-G., Stadelhofer, J.W. Industrial Aromatic Chemistry. Springer-Verlag, New York. 1988. pp. 148-155.</ref> In the [[Lummus process]], the oxidation of toluene to [[benzoic acid]] is conducted separately.

===Miscellaneous methods===
[[File:Amine to Phenol .jpg|class=skin-invert-image|thumb|right|Amine to phenol<ref name=":0"/>]]
[[Phenyldiazonium]] salts hydrolyze to phenol. The method is of no commercial interest since the precursor is expensive.<ref name=":0">{{cite journal|title=Amine to phenol conversion|journal=Synlett|volume=28|issue=13|pages=1641–1645|doi=10.1055/s-0036-1588180|year=2017|last1=Kazem-Rostami|first1=Masoud|s2cid=99294625 }}</ref>
:{{chem2|C6H5NH2 + HCl + NaNO2 -> C6H5OH + N2 + H2O + NaCl}}
[[Salicylic acid]] decarboxylates to phenol.<ref>{{cite journal |last1=Kaeding |first1=Warren W. |title=Oxidation of Aromatic Acids. IV. Decarboxylation of Salicylic Acids |journal=The Journal of Organic Chemistry |date=1 September 1964 |volume=29 |issue=9 |pages=2556–2559 |doi=10.1021/jo01032a016}}</ref>

===Shipping===
Phenol, which is produced and hence transported in large volumes, is shipped in a molten state below {{convert|70|C|F}}. The melting point is lowered and corrosive nature enhanced in the presence of small amounts of water. Typically, stainless steel containers and nitrogen-blanketing are required to prevent discoloration.<ref name="Ullmann"/>

==Exposure and potential toxicity==
Exposure to phenol may occur in people living near [[landfill]]s, hazardous waste sites or factories  manufacturing it.<ref name=cdc/><ref name="tox">{{cite web |title=ToxFAQs: Phenol |url=https://www.atsdr.cdc.gov/es/toxfaqs/es_tfacts115.html |publisher=Agency for Toxic Substances and Disease Registry, US Centers for Disease Control and Prevention |access-date=28 May 2025 |date=6 May 2016}}</ref> Low levels of phenol exposure may occur in consumer products, such as toothpastes and [[throat lozenge]]s, skin or pain treatments, cigarette smoke, and in some foods or water.<ref name=tox/>

Exposure to phenol through any form of ingestion or contact can produce systemic poisoning, with possible symptoms including transient brain stimulation, followed by [[coma]] and [[seizure]]s over minutes to hours following exposure.<ref name=cdc/> Other symptoms may include [[hemolytic anemia]], profuse sweating, hypotension, [[arrhythmia]], [[pulmonary edema]], nausea, vomiting, and diarrhea.<ref name=cdc/><ref name=stat/> Chronic exposure to phenol or its vapor may cause [[Nephrotoxicity|kidney toxicity]], skin lesions, or [[gastrointestinal disease]].<ref name="stat">{{cite web|vauthors=D'Souza RS, Warner NS|title=Phenol nerve block|date=28 August 2023|publisher=StatPearls, US National Library of Medicine|url=https://www.ncbi.nlm.nih.gov/books/NBK525978/|access-date=10 February 2025}}</ref><ref name="merck"/> Phenol is metabolized in the liver, and excreted by the kidneys.<ref name=stat/>

If inhaled, ingested or by skin contact, phenol can enter the blood, possibly causing breathing problems, headaches, or sore eyes.<ref name=cdc/><ref name=tox/><ref name="merck">{{cite book |editor-first=S |editor-last=Budavari |title=The Merck Index: An Encyclopedia of Chemical, Drugs, and Biologicals |publisher=[[Merck & Co.|Merck]] |location=Whitehouse Station, NJ |year=1996}}</ref> High amounts of phenol contacting the skin may cause [[liver disease]], irregular heartbeat, [[seizure]]s, [[coma]], and, rarely, death.<ref name=cdc/><ref name=tox/><ref>{{cite journal |doi=10.1097/00000542-198503000-00030 |last1=Warner |first1=MA |first2=JV |last2=Harper |title=Cardiac dysrhythmias associated with chemical peeling with phenol |journal=Anesthesiology |volume=62 |year=1985 |pages=366–7 |pmid=2579602 |issue=3|doi-access=free }}</ref> Repeated or prolonged skin contact with phenol may cause [[dermatitis]], or even second and third-degree burns.<ref>{{cite journal |title=Phenol burn|vauthors=Lin TM, Lee SS, Lai CS, Lin SD |journal=Burns: Journal of the International Society for Burn Injuries|date=June 2006 |volume=32 |pages=517–21 |pmid=16621299 |issue=4 |doi=10.1016/j.burns.2005.12.016}}</ref> Its corrosive effect on skin and mucous membranes is due to a protein-degenerating effect.<ref name=U/> [[Chemical burn]]s from skin exposures can be decontaminated by washing with [[polyethylene glycol]],<ref>{{cite journal |last1=Brown |first1=VKH |last2=Box |first2=VL |last3=Simpson |first3=BJ |title=Decontamination procedures for skin exposed to phenolic substances |journal=Archives of Environmental Health |volume=30 |year=1975 |pages=1–6 |pmid=1109265 |issue=1 |doi=10.1080/00039896.1975.10666623}}</ref> [[isopropyl alcohol]],<ref>{{cite journal |first1=DM |last1=Hunter |first2=BL |last2=Timerding |first3=RB |last3=Leonard |first4=TH |last4=McCalmont |first5=E |last5=Schwartz |title=Effects of isopropyl alcohol, ethanol, and polyethylene glycol/industrial methylated spirits in the treatment of acute phenol burns |journal=[[Annals of Emergency Medicine]] |volume=21 |year=1992 |pages=1303–7 |doi=10.1016/S0196-0644(05)81891-8 |pmid=1416322 |issue=11}}</ref> or with copious amounts of water.<ref>{{cite journal |first1=TG |last1=Pullin |first2=MN |last2=Pinkerton |first3=RV |last3=Johnston |first4=DJ |last4=Kilian |title=Decontamination of the skin of swine following phenol exposure: a comparison of the relative efficacy of water versus polyethylene glycol/industrial methylated spirits |journal=Toxicol Appl Pharmacol |volume=43 |year=1978 |pages=199–206 |doi=10.1016/S0041-008X(78)80044-1 |pmid=625760 |issue=1|bibcode=1978ToxAP..43..199P }}</ref>

Safety concerns have caused phenol to be banned from use in cosmetic products in the [[European Union]]<ref>{{cite web|url=http://ec.europa.eu/growth/tools-databases/cosing/index.cfm?fuseaction=search.results|title=Prohibited substances in cosmetic product (Annex II, #1175, Phenol) - European Commission|website=ec.europa.eu|language=en|access-date=2018-07-06}}</ref><ref>{{cite web|url=http://ec.europa.eu/growth/tools-databases/cosing/index.cfm?fuseaction=search.details_v2&id=29394|title=CosIng - Cosmetics - GROWTH - European Commission|website=ec.europa.eu|language=en|access-date=2018-07-06}}</ref> and [[Canada]].<ref>{{cite web|url=https://www.canada.ca/en/health-canada/services/consumer-product-safety/cosmetics/cosmetic-ingredient-hotlist-prohibited-restricted-ingredients/hotlist.html#t1p|title=Cosmetic Ingredient Hotlist - Canada.ca|last=Canada|first=Health|website=www.canada.ca|language=en|access-date=2018-07-06|date=2004-06-18}}</ref><ref>{{cite web|url=https://www.canada.ca/en/health-canada/services/consumer-product-safety/cosmetics/cosmetic-ingredient-hotlist-prohibited-restricted-ingredients.html|title=Cosmetic Ingredient Hotlist: Prohibited and Restricted Ingredients - Canada.ca|last=Canada|first=Health|website=www.canada.ca|language=en|access-date=2018-07-06|date=2004-06-18}}</ref>

Besides its [[hydrophobic]] effects, another possible mechanism for the toxicity of phenol is the formation of [[phenoxyl]] [[free radical|radicals]].<ref>{{cite journal|last2=McKarns|first2=Susan C|last3=Smith|first3=Carr J|last4=Doolittle|first4=David J|date=June 15, 2000|title=Comparative QSAR evidence for a free-radical mechanism of phenol-induced toxicity|journal=Chemico-Biological Interactions|volume=127|issue=1|pages=61–72|doi=10.1016/S0009-2797(00)00171-X|pmid=10903419|first1=Corwin|last1=Hanscha|bibcode=2000CBI...127...61H }}</ref>

==Uses==
===Chemicals===
The major uses of phenol, consuming two thirds of its production, involve its conversion to precursors for plastics. [[Condensation reaction|Condensation]] with [[acetone]] gives [[bisphenol-A]], a key precursor to [[polycarbonate]]s and [[epoxy|epoxide]] resins. Condensation of phenol, [[Alkylphenol|alkylphenols]], or [[Diphenol|diphenols]] with [[formaldehyde]] gives [[phenolic resin]]s, an example of which is [[Bakelite]].<ref>{{Citation |last1=Lorenc |first1=John F. |title=Alkylphenols |date=2003 |encyclopedia=Kirk-Othmer Encyclopedia of Chemical Technology |url=https://onlinelibrary.wiley.com/doi/abs/10.1002/0471238961.0112112512151805.a01.pub2 |access-date=2025-05-15 |publisher=John Wiley & Sons, Ltd |language=en |doi=10.1002/0471238961.0112112512151805.a01.pub2 |isbn=978-0-471-23896-6 |last2=Lambeth |first2=Gregory |last3=Scheffer |first3=William|url-access=subscription }}</ref><ref>{{Citation |last1=Pizzi |first1=A. |title=Chapter 2 - Phenol-formaldehyde resins |date=2022-01-01 |work=Handbook of Thermoset Plastics (Fourth Edition) |pages=13–40 |editor-last=Dodiuk |editor-first=Hanna |url=https://www.sciencedirect.com/science/article/abs/pii/B9780128216323000130 |access-date=2025-05-15 |series=Plastics Design Library |place=Boston |publisher=William Andrew Publishing |isbn=978-0-12-821632-3 |last2=Ibeh |first2=C. C.}}</ref> Partial [[hydrogenation]] of phenol gives [[cyclohexanone]],<ref name="Ullmann Cyclohexanes">{{Ullmann |last=Musser |first=Michael T. |title=Cyclohexanol and Cyclohexanone |doi=10.1002/14356007.a08_217.pub2}}</ref> a precursor to [[nylon]]. Nonionic [[detergent]]s are produced by [[alkylation]] of phenol to give the alkylphenols, e.g., [[nonylphenol]], which are then subjected to [[ethoxylation]].<ref name="Ullmann"/>

Phenol is also a versatile precursor to a large collection of drugs, most notably [[aspirin]] but also many [[herbicide]]s and [[pharmaceutical drug]]s. Phenol is a component in [[liquid–liquid extraction|liquid–liquid]] [[phenol–chloroform extraction]] technique used in [[molecular biology]] for obtaining [[nucleic acid]]s from tissues or cell culture samples. Depending on the pH of the solution either [[DNA]] or [[RNA]] can be extracted.

Phenol is so inexpensive that it also attracts many small-scale uses. It is a component of industrial [[paint stripper]]s used in the aviation industry for the removal of epoxy, polyurethane and other chemically resistant coatings.<ref>{{cite web|url=https://www.callingtonhaven.com/_assets/paint_strippers/ch207.pdf|title=CH207 Aircraft paintstripper, phenolic, acid|date=14 October 2009|publisher=Callington|access-date=25 August 2015|archive-date=23 September 2015|archive-url=https://web.archive.org/web/20150923195922/http://www.callingtonhaven.com/_assets/paint_strippers/ch207.pdf}}</ref>

===Topical anesthetic===
Concentrated liquid phenol can be used [[topical medication|topically]] as a local [[anesthetic]] for [[otology]] procedures, such as [[myringotomy]] and [[tympanotomy]] tube placement, as an alternative to general anesthesia or other local anesthetics.<ref name="drugs">{{cite web|title=Phenol (oromucosal)|url=https://www.drugs.com/cdi/phenol-spray.html |publisher=Drugs.com|date=10 December 2023|access-date=3 February 2025}}</ref> Phenol spray, with phenol as the active ingredient, is used medically to treat sore throat.<ref name=drugs/> It is the active ingredient in some oral [[analgesia|analgesics]].<ref name=drugs/>

Concentrated phenol liquids are used for permanent treatment of ingrown toe and finger nails, a procedure known as a chemical [[matrixectomy]]. The procedure was first described by Otto Boll in 1945.<ref>{{Cite journal |last1=Espensen |first1=Eric H. |last2=Nixon |first2=Brent P. |last3=Armstrong |first3=David G. |date=2002-05-01 |title=Chemical Matrixectomy for Ingrown Toenails: Is There an Evidence Basis to Guide Therapy? |url=https://japmaonline.org/view/journals/apms/92/5/87507315-92-5-287.xml|journal=Journal of the American Podiatric Medical Association |language=en |volume=92 |issue=5 |pages=287–295 |doi=10.7547/87507315-92-5-287 |pmid=12015409 |issn=1930-8264|url-access=subscription }}</ref>

===Nerve block===
{{See also|Nerve block}}
Phenol is used as a chemical [[denervation]] agent in [[analgesia]] treatment, such as for [[spasticity]], arthritis, or cancer pain.<ref name=stat/> Its effect on the nerve is to [[Denaturation (biochemistry)|denature]] protein, diminish nerve fat and [[myelin]] content, and interrupt sensory transmission to the brain.<ref name=stat/> If successful, pain relief may last for weeks to two years.<ref name=stat/> Complications may include pain on injection, bleeding, or infection.<ref name=stat/>

Clinical studies from 2023-25 reported that local injection of phenol (1.5&ndash;3 ml of 6% phenol in sterile water) at three to five [[Knee#Nerves|sensory knee nerves]] was effective as a [[neurolysis|neurolytic]] treatment to relieve pain associated with chronic [[osteoarthritis]].<ref name="tay">{{cite journal |vauthors=Tay MR, Mittal N, Yao S, Farag J |title=Chemical neurolysis of genicular nerves for chronic non-cancer knee pain: a scoping review |journal=Pain Medicine |volume=26 |issue=2 |pages=76–89 |date=February 2025 |pmid=39475441 |doi=10.1093/pm/pnae109 |url=https://academic.oup.com/painmedicine/article/26/2/76/7852839|url-access=subscription }}</ref><ref name="wilk">{{cite journal |vauthors=Wilkinson AJ, Chai T, Roldan CJ, Huh BK |title=Genicular nerve neurolysis with phenol for chronic knee pain: A case series |journal=Interventional Pain Medicine |volume=2 |issue=1 |article-number=100182 |date=March 2023 |pmid=39239601 |pmc=11372894 |doi=10.1016/j.inpm.2023.100182}}</ref> The phenol method may be used for people who did not experience pain relief from [[Radiofrequency_ablation#Knees|radiofrequency ablation]] of knee nerves.<ref name=tay/><ref name=wilk/>

==History==
[[File:Bottle of Phenol.jpg|thumb|right|Bottle of Calvert's phenol antiseptic, [[Thackray Museum of Medicine]]<ref>{{Cite web |title=182.095 {{!}} Collections Online |url=https://collections.thackraymuseum.co.uk/object-182-095 |access-date=2024-05-30 |website=collections.thackraymuseum.co.uk}}</ref>]]
Phenol was discovered in 1834 by [[Friedlieb Ferdinand Runge]], who extracted it (in impure form) from [[coal tar]].<ref>F. F. Runge (1834) [https://babel.hathitrust.org/cgi/pt?id=wu.89048351654&view=1up&seq=81 "Ueber einige Produkte der Steinkohlendestillation"] (On some products of coal distillation), ''Annalen der Physik und Chemie'', '''31''': 65-78. On page 69 of volume 31, Runge names phenol "Karbolsäure" (coal-oil-acid, carbolic acid). Runge characterizes phenol in: F. F. Runge (1834) [http://babel.hathitrust.org/cgi/pt?id=wu.89048351654#page/308/mode/1up "Ueber einige Produkte der Steinkohlendestillation,"] ''Annalen der Physik und Chemie'', '''31''': 308-328.</ref> Runge called phenol "Karbolsäure" (coal-oil-acid, carbolic acid). Coal tar remained the primary source until the development of the [[petrochemical industry]]. French chemist [[Auguste Laurent]] extracted phenol in its pure form, as a derivative of benzene, in 1841.<ref>Auguste Laurent (1841) [http://gallica.bnf.fr/ark:/12148/bpt6k347443/f194.image "Mémoire sur le phényle et ses dérivés"] (Memoir on benzene and its derivatives), ''Annales de Chimie et de Physique'', series 3, '''3''': 195-228. On page 198, Laurent names phenol "hydrate de phényle" and "l'acide phénique".</ref> In 1836, Auguste Laurent coined the name "phène" for benzene;<ref>Auguste Laurent (1836) "Sur la chlorophénise et les acides chlorophénisique et chlorophénèsique," ''Annales de Chemie et de Physique'', vol. 63, pp. 27–45, see [https://books.google.com/books?id=Lx0AAAAAMAAJ&pg=PA44 p. 44]: Je donne le nom de phène au radical fondamental des acides précédens (φαινω, j'éclaire), puisque la benzine se trouve dans le gaz de l'éclairage. (I give the name of "phène" (φαινω, I illuminate) to the fundamental radical of the preceding acid, because benzene is found in illuminating gas.)</ref> this is the root of the word "phenol" and "[[phenyl]]". In 1843, French chemist [[Charles Frédéric Gerhardt|Charles Gerhardt]] coined the name "phénol".<ref>Gerhardt, Charles (1843) [http://babel.hathitrust.org/cgi/pt?id=uva.x002489028;view=1up#page/215/mode/1up "Recherches sur la salicine,"] ''Annales de Chimie et de Physique'', series 3, '''7''': 215-229. Gerhardt coins the name "phénol" on page 221.</ref>

The [[antiseptic]] properties of phenol were used by Sir [[Joseph Lister]] in his pioneering technique of antiseptic surgery. Lister decided that the wounds had to be thoroughly cleaned. He then covered the wounds with a piece of rag or lint<ref>{{cite web |first=Joseph |last=Lister |title=Antiseptic Principle Of The Practice Of Surgery |year=1867 |url=https://sourcebooks.fordham.edu/mod/1867lister.asp}}</ref> covered in phenol. The skin irritation caused by continual exposure to phenol eventually led to the introduction of aseptic (germ-free) techniques in surgery. Lister's work was inspired by the works and experiments of his contemporary [[Louis Pasteur]] in sterilizing various biological media. He theorized that if germs could be killed or prevented, no infection would occur. Lister reasoned that a chemical could be used to destroy the micro-organisms that cause infection.<ref>{{cite book|last1=Hollingham|first1=Richard|title=Blood and Guts: A History of Surgery|date=2008|publisher=BBC Books - Random House|isbn=978-1-4070-2453-0|page=61}}</ref>

Meanwhile, in [[Carlisle]], England, officials were experimenting with [[sewage treatment]] using carbolic acid to reduce the smell of sewage [[Cesspit|cesspools]]. Having heard of these developments, and having previously experimented with other chemicals for antiseptic purposes without much success, Lister decided to try carbolic acid as a wound antiseptic. He had his first chance on August 12, 1865, when he received a patient: an eleven-year-old boy with a tibia bone fracture which pierced the skin of his lower leg. Ordinarily, amputation would be the only solution. However, Lister decided to try carbolic acid. After setting the bone and supporting the leg with splints, he soaked clean cotton towels in undiluted carbolic acid and applied them to the wound, covered with a layer of tin foil, leaving them for four days. When he checked the wound, Lister was pleasantly surprised to find no signs of infection, just redness near the edges of the wound from mild burning by the carbolic acid. Reapplying fresh bandages with diluted carbolic acid, the boy was able to walk home after about six weeks of treatment.<ref name="BBC Books - Randomhouse">{{cite book|last1=Hollingham|first1=Richard|title=Blood and Guts: A History of Surgery|date=2008|publisher=BBC Books - Random House|isbn=978-1-4070-2453-0|page=62}}</ref>

<blockquote>By 16 March 1867, when the first results of Lister's work were published in the Lancet, he had treated a total of eleven patients using his new antiseptic method. Of those, only one had died, and that was through a complication that was nothing to do with Lister's wound-dressing technique. Now, for the first time, patients with compound fractures were likely to leave the hospital with all their limbs intact
:— Richard Hollingham, ''Blood and Guts: A History of Surgery'', p. 62<ref name="BBC Books - Randomhouse"/></blockquote>

<blockquote>Before antiseptic operations were introduced at the hospital, there were sixteen deaths in thirty-five surgical cases. Almost one in every two patients died. After antiseptic surgery was introduced in the summer of 1865, there were only six deaths in forty cases. The mortality rate had dropped from almost 50 per cent to around 15 per cent. It was a remarkable achievement
:— Richard Hollingham, ''Blood and Guts: A History of Surgery'', p. 63<ref>{{cite book|last1=Hollingham|first1=Richard|title=Blood and Guts: A History of Surgery|date=2008|publisher=BBC Books - Randomhouse|isbn=978-1-4070-2453-0|page=63}}</ref></blockquote>

Phenol was the main ingredient of the "carbolic smoke ball," an ineffective device marketed in London in the 19th century as protection against influenza and other ailments, and the subject of the famous law case ''[[Carlill v Carbolic Smoke Ball Company]]''. In the tort law case of ''[[Roe v Minister of Health]]'', phenol was used to sterilize [[anaesthetic]] packed in [[ampoule]]s, in which it contaminated the anaesthetic through invisible micro-cracks and caused [[paraplegia]] to the plaintiffs.

===Second World War===
The [[Phenol#Exposure and potential toxicity|toxic effect of phenol]] on the central nervous system causes sudden collapse and loss of consciousness in both humans and animals; a state of cramping precedes these symptoms because of the motor activity controlled by the central nervous system.<ref name=U/> Injections of phenol were used as a means of individual execution by [[Nazi Germany]] during the [[Second World War]].<ref name=TysonNOVA>[https://www.pbs.org/wgbh/nova/holocaust/experiside.html#pois ''The Experiments''] by Peter Tyson. NOVA</ref> It was originally used by the Nazis in 1939 as part of the mass-murder of disabled people under ''[[Aktion T4]]''.<ref name=NaziDrs>[http://www.holocaust-history.org/lifton/LiftonT254.shtml ''The Nazi Doctors''] {{Webarchive|url=https://web.archive.org/web/20171022104811/http://www.holocaust-history.org/lifton/LiftonT254.shtml |date=2017-10-22 }}, Chapter 14, Killing with Syringes: Phenol Injections. By Dr. Robert Jay Lifton</ref> The Germans learned that extermination of smaller groups was more economical by injection of each victim with phenol. Phenol injections were given to thousands of people. [[Maximilian Kolbe]] was also murdered with a phenol injection after surviving two weeks of dehydration and starvation in [[Auschwitz]] when he volunteered to die in place of [[Franciszek Gajowniczek|a stranger]]. Approximately one gram is sufficient to cause death.<ref name="carbolic">{{cite web |publisher=Johannes Kepler University |location=Linz, Austria |work=Auschwitz: Final Station Extermination |title=Killing through phenol injection |url=http://www.wsg-hist.uni-linz.ac.at/AUSCHWITZ/HTML/Phenol.html |archive-url=https://web.archive.org/web/20061112224223/http://www.wsg-hist.uni-linz.ac.at/AUSCHWITZ/HTML/Phenol.html|archive-date=2006-11-12 }}</ref>

==Occurrences==
Phenol is a normal metabolic product, excreted in quantities up to 40&nbsp;mg/L in human urine.<ref name=U>{{cite encyclopedia |pages=589–604 |volume=25 |publisher=Wiley-VCH |date=2003 |contribution=Phenol |title=Ullmann's Encyclopedia of Industrial Chemistry}}</ref> The [[temporal gland]] secretion of male [[elephant]]s showed the presence of phenol and [[4-methylphenol]] during [[musth]].<ref>{{cite journal|doi=10.1016/S0031-9384(99)00114-6|title=Physiological Correlates of Musth|year=1999|last1=Rasmussen|first1=L.E.L|last2=Perrin|first2=Thomas E|journal=Physiology & Behavior|volume=67|issue=4|pages=539–49|pmid=10549891|s2cid=21368454}}</ref> It is also one of the chemical compounds found in [[castoreum]]. This compound is ingested from the plants the beaver eats.<ref>The Beaver: Its Life and Impact. Dietland Muller-Schwarze, 2003, page 43 ([https://books.google.com/books?id=HZ5WjXB5Pr8C&dq=Castoreum+beekeeping&pg=PA43 book at google books])</ref>

Phenol is a measurable component in the aroma and taste of the distinctive [[Islay whisky|Islay scotch whisky]],<ref name="auto">{{cite web |title=Peat, Phenol and PPM, by Dr P. Brossard |url=http://www.whisky-news.com/En/reports/Peat_phenol_ppm.pdf |access-date=2008-05-27}}</ref> generally ~30&nbsp;[[parts per million|ppm]], but it can be over 160&nbsp;ppm in the malted [[barley]] used to produce [[whisky]].<ref>{{cite web|title=Bruichladdich|url=http://www.bruichladdich.com/the-whisky/octomore|website=Bruichladdich|publisher=BDCL|access-date=8 August 2015|archive-url=https://web.archive.org/web/20160421054437/http://www.bruichladdich.com/the-whisky/octomore|archive-date=21 April 2016}}</ref> This amount is different from and presumably higher than the amount in the distillate.<ref name="auto"/>

==Biodegradation==
''[[Cryptanaerobacter phenolicus]]'' is a bacterium species that produces [[benzoic acid|benzoate]] from phenol via [[4-hydroxybenzoate]].<ref name=Juteau>{{cite journal|doi=10.1099/ijs.0.02914-0|title=''Cryptanaerobacter phenolicus'' gen. nov., sp. nov., an anaerobe that transforms phenol into benzoate via 4-hydroxybenzoate|year=2005|last1=Juteau|first1=P.|journal=International Journal of Systematic and Evolutionary Microbiology|volume=55|pages=245–50|pmid=15653882|last2=Côté|first2=V|last3=Duckett|first3=MF|last4=Beaudet|first4=R|last5=Lépine|first5=F|last6=Villemur|first6=R|last7=Bisaillon|first7=JG|issue=Pt 1|doi-access=free}}</ref> ''[[Rhodococcus phenolicus]]'' is a bacterium species able to degrade phenol as sole carbon source.<ref>{{cite journal|pmid=16261859|doi=10.1016/j.syapm.2005.05.011|title=''Rhodococcus phenolicus'' sp. nov., a novel bioprocessor isolated actinomycete with the ability to degrade chlorobenzene, dichlorobenzene and phenol as sole carbon sources|year=2005|last1=Rehfuss|first1=Marc|last2=Urban|first2=James|journal=Systematic and Applied Microbiology|volume=28|issue=8|pages=695–701|bibcode=2005SyApM..28..695R }}</ref>

==Naming==
{{Main|Phenols}}
The word ''phenol'' is also used to refer to any compound that contains a six-membered [[aromatic]] ring, bonded directly to a [[hydroxyl group]] (-OH). Thus, phenols are a class of [[organic compound]]s of which the phenol discussed in this article is the simplest member.

==See also==
*[[Bamberger rearrangement]]
*[[Claisen rearrangement]]
*[[Cresol]]
*[[Fries rearrangement]]
*[[Polyphenol]]

==References==
{{Reflist|30em}}

==External links==
{{Wiktionary|phenol}}
{{Wikiquote}}
{{EB1911 poster|Carbolic Acid}}
*[http://www.inchem.org/documents/icsc/icsc/eics0070.htm International Chemical Safety Card 0070]
*[https://hazard.com//msds/mf/baker/baker/files/p1949.htm Phenol Material Safety Data Sheet]
*[http://www.npi.gov.au/resource/phenol National Pollutant Inventory: Phenol Fact Sheet]
*[https://www.cdc.gov/niosh/npg/npgd0493.html NIOSH Pocket Guide to Chemical Hazards]
*[https://www.cdc.gov/niosh/topics/phenol/ CDC - Phenol - NIOSH Workplace Safety and Health Topic]
*[https://web.archive.org/web/20051012222001/http://www-cie.iarc.fr/htdocs/monographs/vol71/027-phenol.html IARC Monograph: "Phenol"]
*[https://tenwatts.blogspot.com/2007/08/phenol-edison-bayer-and-records.html Arcane Radio Trivia outlines competing uses for Phenol circa 1915]

{{Antiseptics and disinfectants}}
{{Throat preparations}}

{{Authority control}}

[[Category:Antiseptics]]
[[Category:Commodity chemicals]]
[[Category:Oxoacids]]
[[Category:Phenyl compounds]]
[[Category:1834 in science]]
[[Category:Substances discovered in the 19th century]]
[[Category:Over-the-counter drugs in the United States]]