Editing Phenol (section)

==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 |url-status=dead }}</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 |url-status=dead |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>