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In [[organic chemistry]], '''phenols''', sometimes called '''phenolics''', are a class of [[chemical compound]]s consisting of a [[hydroxyl]] [[Functional group|group]] (-[[Oxygen|O]] [[Hydrogen|H]]) attached to an [[aromatic hydrocarbon]] group. The simplest of the class is [[phenol]] (C<sub>6</sub>H<sub>5</sub>OH).
[[Image:Phenol chemical structure.png|thumb|right|Phenol - the simplest of the phenols.]]

Although similar to [[alcohol]]s, phenols have unique properties and are not classified as alcohols (since the hydroxyl group is not bonded to a ''saturated'' carbon atom). They have relatively higher [[acid]]ities due to the aromatic ring tightly coupling with the oxygen and a relatively loose bond between the [[oxygen]] and [[hydrogen]]. The acidity of the hydroxyl group in phenols is commonly intermediate between that of [[aliphatic]] alcohols and [[carboxylic acid]]s (their pK<sub>a</sub> is usually comprised between 10 and 12). Loss of a positive hydrogen ion (H<sup>+</sup>) from the hydroxyl group of a phenol forms a negative '''phenolate''' ion.

Some phenols are germicidal and are used in formulating disinfectants. Others possess [[estrogen]]ic or [[endocrine disruptor|endocrine disrupting]] activity.

==Synthesis of phenols==<!-- This section is linked from [[Organic reaction]] -->
Several laboratory methods for the synthesis of phenols:
* by an ester rearrangement in the [[Fries rearrangement]]
* by a rearrangement of N-phenylhydroxylamines in the [[Bamberger rearrangement]]
* by [[hydrolysis]] of phenolic [[ester]]s or [[ether]]s
* by reduction of [[quinone]]s
* by replacement of an aromatic amine by an hydroxyl group with water and sodium bisulfite in the [[Bucherer reaction]]
* by [[hydrolysis]] of [[diazonium salt]]s
* by oligomerisation with formaldehyde + base catalysed reaction with epichlorohydrine to epoxi resin components
* by reaction with acetone/ketones to e.g. [[Bisphenol A]], an important monomer for resins, e.g. polycarbonate(PC), epoxi resins
* by a [[rearrangement reaction]] of dienones <ref>related to [[quinone]]s, see for example the [[Zincke-Suhl reaction]]</ref> in the '''dienone phenol rearrangement''' <ref>''Advanced organic Chemistry, Reactions, mechanisms and struc''ture 3ed. page Jerry March ISBN 0-471-85472-7 </ref>:
:[[Image:DienonePhenolRearrangement.png|400px|The dienone phenol rearrangement]]

==Reactions of phenols==<!-- This section is linked from [[Organic reaction]] -->
Phenols react in a wide variety of ways.
* [[Esterification]] reactions and [[ether]] formation
* [[Electrophilic aromatic substitution]]s as the hydroxyl group is [[activating group|activating]], for example synthesis of [[calixarene]]s <ref>p-tert-butylcalix[8]arene, [[Organic Syntheses]], CV 8, 80 [http://www.orgsynth.org/orgsyn/prep.asp?prep=cv8p0080 Article]</ref>
* Reaction of naphtols and hydrazines and sodium bisulfite in the [[Bucherer carbazole synthesis]]
* Oxidative cleavage, for instance cleavage of 1,2-dihydroxybenzene to the monomethylester of 2,4 hexadienedioic acid with oxygen, copper chloride in pyridine <ref>2,4-Hexadienedioic acid, monomethyl ester, (Z,Z)- [[Organic Syntheses]], Coll. Vol. 8, p.490 (1993); Vol. 66, p.180 (1988) [http://www.orgsynth.org/orgsyn/prep.asp?prep=cv8p0490 Article]
</ref>
* Oxidative de-aromatization to [[quinone]]s also known as the [[Teuber reaction]]. Oxidizing reagents are [[Fremy's salt]] <ref>2,5-Cyclohexadiene-1,4-dione, 2,3,5-trimethyl [[Organic Syntheses]], Coll. Vol. 6, p.1010 (1988); Vol. 52, p.83 (1972) [http://www.orgsynth.org/orgsyn/prep.asp?prep=cv6p1010 Abstract].
</ref> and [[oxone]] <ref>''Oxidative De-aromatization of para-Alkyl Phenols into para-Peroxyquinols and para-Quinols Mediated by Oxone as a Source of Singlet Oxygen'' M. Carmen Carreño, Marcos González-López, Antonio Urbano [[Angewandte Chemie International Edition]] Volume 45, Issue 17 , Pages 2737 - 2741 2006 [http://dx.doi.org/10.1002/anie.200504605 Abstract]</ref>. In reaction depicted below 3,4,5-trimethylphenol reacts with [[singlet oxygen]] generated from [[oxone]]/[[sodium carbonate]] in an [[acetonitrile]]/water mixture to a para-peroxyquinole. This [[hydroperoxide]] is oxidized to the quinole with [[sodium thiosulphate]].
:[[Image:OxonePhenolDearomatization.png|600px|Oxone Phenol Dearomatization]]
* Phenols are oxidized to [[benzenediol]]s in the [[Elbs persulfate oxidation]]
* Phenolate [[anions]] (deriving from phenols by the loss of H<sup>+</sup>) can act as [[ligands]] towards metal [[cations]]

==Phenolic compounds==
:''For a full list, see [[:Category:Phenols]]''

{|align="center"  class="wikitable" style="background-color:white;"
|[[Phenol]]||the parent compound, used as an [http://www.pedicure-tips.com/Pedicure-Disinfectant-Phenolics.html disinfectant] and for [[chemical synthesis]]
|-
|[[BHT]]||(butylated hydroxytoluene) - a fat-soluble [[antioxidant]] and [[food additive]]
|-
|[[Capsaicin]]||the pungent compound of [[chilli pepper]]s
|-
|[[Bisphenol A]]||and other bisphenols produced from ketones and phenol / cresol
|-
|[[Chavibetol]]||from ''[[betel]]'', used as a flavouring

|-
|[[Cresol]]||found in [[coal tar]] and [[creosote]]
|-
|[[Estradiol]]||[[estrogen]] - hormones
|-
|[[Eugenol]]||the main constituent of the [[essential oil]] of [[clove]]
|-
|[[Gallic acid]]||found in [[gallnuts]]
|-
|[[Guaiacol]]||(2-methoxyphenol) - has a smokey [[flavor]], and is found in [[roasted]] [[coffee]], [[whisky]], and [[smoke]]
|-
|[[4-Nonylphenol]]||a breakdown product of [[detergents]] and [[nonoxynol-9]]
|-
|[[Orthophenyl phenol]]||a [[fungicide]] used for waxing [[citrus fruit]]s
|-
|[[Picric acid]]||(trinitrophenol) - an [[explosive material]]
|-
|[[Phenolphthalein]]||[[pH indicator]]
|-
|[[Polyphenol]]||e.g. [[flavonoid]]s and [[tannin]]s
|-
|[[Raspberry ketone]]|| a compound with an intense [[raspberry]] smell
|-
|[[Serotonin]] / [[dopamine]] / [[adrenaline]] / [[noradrenaline]] || natural [[neurotransmitters]]
|-
|[[Thymol]]|| (2-Isopropyl-5-methyl phenol) - an [[antiseptic]] that is used in [[mouthwash]]es
|-
|[[Tyrosine]]|| an [[amino acid]]
|-
|[[Xylenol]]|| |-
|}


===Medicinals===

{|align="center"  class="wikitable" style="background-color:white;"
|[[Cannabinoids]]||the active constituents of ''[[Cannabis sativa|cannabis]]''
|-
|[[Diethylstilbestrol]]||a synthetic estrogen with a [[stilbene]] structure
|-
|[[L-DOPA]]||a synthetic estrogen with a [[stilbene]] structure
|-
|[[Methyl salicylate]]||the major constituent of the essental oil of [[wintergreen]]
|-
|[[Propofol]]||a short-acting intravenous [[Anesthesia|anesthetic]] agent
|-
|[[Psilocin]]||a [[Psychedelics, dissociatives and deliriants|hallucinogenic]] [[alkaloid]] of ''[[Psilocybe]]'' [[mushroom]]s
|-
|[[Salicylic acid]]||a [[plant hormone]] used for its [[analgesic]], [[antipyretic]] and [[anti-inflammatory]] properties, also a precursor compound to [[Aspirin]]
|-
|[[Trichlorophenylmethyliodosalicyl]]||the main component of [[TCP (antiseptic)|TCP]], an antiseptic.
|-
|}


==References==
<references/>

[[Category:Phenols|*]]
[[Category:Organic chemistry]]
[[Category:Disinfectants]]

[[cs:Fenoly]]
[[da:Fenoler]]
[[de:Phenole]]
[[es:Fenol]]
[[et:Fenoolid]]
[[fr:Phénol (groupe)]]
[[it:Fenoli]]
[[ko:페놀류]]
[[mk:Фенол (класа)]]
[[he:פנול]]
[[ja:フェノール類]]
[[pl:Fenole]]
[[ru:Фенолы]]
[[sk:Fenoly]]
[[zh:酚]]