Phenols 23865 220366943 2008-06-19T14:48:12Z 129.105.122.253 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's tight 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 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 bisulfide 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. * [[Esterfication]] 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 thiosulfate]]. :[[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]]|| |-used in antiseptics & disinfecticides |} ===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 |- |[[Levodopa|L-DOPA]]||a synthetic estrogen with a [[stilbene]] structure |- |[[Methyl salicylate]]||the major constituent of the essential 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]] |- |[[TCP (antiseptic)|Trichlorophenylmethyliodosalicyl]]||the main component of [[TCP (antiseptic)|TCP]], an antiseptic. |- |} ==References== <references/> == External links == *[http://www.mdpi.org/molecules/specialissues/phenolics.htm Special Issue on Phenolics (flavonoids and non-flavonoids)] [[Category:Phenols|*]] [[Category:Organic chemistry]] [[Category:Disinfectants]] [[bs:Fenoli]] [[cs:Fenoly]] [[da:Fenoler]] [[de:Phenole]] [[et:Fenoolid]] [[es:Fenoles (metabolitos secundarios de las plantas)]] [[fr:Phénol (groupe)]] [[ko:페놀류]] [[it:Fenoli]] [[mk:Фенол (класа)]] [[ja:フェノール類]] [[pl:Fenole]] [[ru:Фенолы]] [[sk:Fenoly]] [[zh:酚]]