Phenol
24085
225319324
2008-07-13T01:59:00Z
76.94.193.196
/* Second World War */
{{Chembox new
| Name = '''Phenol'''
| ImageFileL1 = Phenol2.svg
| ImageSizeL1 = 75px
| ImageFileR1 = Phenol-2D-skeletal.png
| ImageSizeR1 = 75px
| ImageFileL2 = Phenol-3D-balls.png
| ImageSizeL2 = 100px
| ImageFileR2 = Phenol-3D-vdW.png
| ImageSizeR2 = 100px
| IUPACName = Phenol
| OtherNames = Carbolic Acid<br/>Benzenol<br/>Phenylic Acid<br/>Hydroxybenzene<br />Phenic acid
| Section1 = {{Chembox Identifiers
| SMILES = Oc1ccccc1
| CASNo = 108-95-2
| RTECS = SJ3325000
| InChI=1/C6H6O/c7-6-<br/>4-2-1-3-5-6/h1-5,7H
}}
| Section2 = {{Chembox Properties
| Formula = C<sub>6</sub>H<sub>5</sub>OH
| MolarMass = 94.11 g/mol
| Appearance = White Crystalline Solid
| Density = 1.07 g/cm³
| Solubility = 8.3 g/100 ml (20 °C)
| MeltingPt = 40.5 °C
| BoilingPt = 181.7 °C
| pKa = 9.95
| Dipole = 1.7 [[Debye|D]]
}}
| Section7 = {{Chembox Hazards
| NFPA-H = 4
| NFPA-F = 2
| NFPA-R =
| FlashPt = 79 °C
| EUClass = Toxic ('''T''')<br/>[[Mutagen|Muta. Cat. 3]]<br/>Corrosive ('''C''')
}}
| Section8 = {{Chembox Related
| OtherCpds = [[Benzenethiol]]
}}
}}
'''Phenol''', also known under an older name of '''carbolic acid''', is a toxic, colourless [[crystal]]line [[solid]] with a sweet tarry odor. It is a significant component in the aroma
of Islay [[scotch whisky]].<ref>{{cite web | title= Peat, Phenol and PPM, by Dr P. Brossard | url=http://www.whisky-news.com/En/reports/Peat_phenol_ppm.pdf | accessdate=2008-05-27}}</ref> Its [[chemical formula]] is [[Carbon|C]]<sub>6</sub>[[Hydrogen|H]]<sub>5</sub>[[Oxygen|O]][[Hydrogen|H]] and its structure is that of a [[hydroxyl]] [[Functional group|group]] (-OH) [[chemical bond|bonded]] to a [[phenyl ring]]; it is thus an [[Simple aromatic ring|aromatic compound]].
==Phenols==
{{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). In effect, phenols are a class of [[organic compound]]s of which the phenol discussed in this article is the simplest member.
==Properties==
Phenol has a limited [[solubility]] in water (8.3 g/100 ml). It is slightly acidic: The phenol molecule has weak tendencies to lose the H<sup>+</sup> ion from the hydroxyl group, resulting in the highly water-soluble '''phenoxide''' [[anion]] C<sub>6</sub>H<sub>5</sub>O<sup>−</sup>. Compared to [[aliphatic]] [[alcohol]]s, phenol shows much higher acidity; it even reacts with [[aqueous]] NaOH to lose H<sup>+</sup>, whereas [[aliphatic]] [[alcohol]]s do not. One explanation for the increased acidity is [[resonance stabilization]] of the phenoxide anion by the aromatic ring. In this way, the negative charge on oxygen is shared by the ortho and para carbon atoms<ref>''Organic Chemistry'' 2nd Ed. John McMurry ISBN 0534079687</ref>. In another explanation, increased acidity is the result of orbital overlap between the oxygen's lone pairs and the aromatic system<ref>{{cite web | publisher=Jim Clark | work =ChemGuide | title=The Acidity of Phenol|url=http://www.chemguide.co.uk/organicprops/phenol/acidity.html| accessdate=2007-08-05}}</ref>. In a third, the dominant effect is the [[inductive effect|induction]] from the [[Orbital hybridisation|sp² hybridised carbons]]{{Clarifyme|date=October 2007}}; the comparatively more powerful inductive withdrawal of electron density that is provided by the sp² system compared to an sp³ system allows for great stabilization of the oxyanion. In making this conclusion, one can examine the [[Acid dissociation constant|pK<sub>a</sub>]] of the [[enol]] of [[acetone]], which is 10.9 in comparison to phenol with a pK<sub>a</sub> of 10.0.<ref>For further reading on the fine points of this topic, see [http://isites.harvard.edu/fs/docs/icb.topic93502.files/Lectures_and_Handouts/20-Acidity_Concepts.pdf David A. Evans]'s explanation.</ref>
==Production==
Phenol can be made from the partial [[Redox|oxidation]] of [[benzene]], the [[reduction]] of [[benzoic acid]], by the [[cumene process]], or by the [[Raschig process]]. It can also be found as a product of [[coal]] oxidation.
==Uses==
Phenol has [[antiseptic]] properties, and was used by Sir [[Joseph Lister]] (1827-1912) in his pioneering technique of antiseptic surgery, though the skin irritation caused by continual exposure to phenol eventually led to the substitution of aseptic (germ-free) techniques in surgery. Lister decided that the wounds themselves had to be thoroughly cleaned. He then covered the wounds with a piece of lint covered in carbolic acid. It is also the active ingredient in some oral anesthetics such as [[Chloraseptic]] spray. Phenol was also the main ingredient of the [[Carbolic Smoke Ball]], a device marketed in London in the 19th century as protecting the user against influenza and other ailments. In the early part of the 20th century, it was used in the [[Battle Creek Sanitarium]] to discourage [[female masturbation]] by applying it to the clitoris.<ref>{{cite web | title= Plain Facts for Old and Young, by J.H. Kellog | url=http://www.mum.org/kellog10.htm | accessdate=2008-05-17}}</ref>
It is also used in the production of drugs (it is the starting material in the industrial production of [[aspirin]]), [[herbicide]]s, and [[chemical synthesis|synthetic]] [[resins]] ([[Bakelite]], one of the first synthetic resins to be manufactured, is a [[polymer]] of phenol with [[formaldehyde]]). Exposure of the [[skin]] to concentrated phenol solutions causes [[chemical burn]]s which may be severe; in [[laboratory|laboratories]] where it is used, it is usually recommended that [[polyethylene glycol]] solution is kept available for washing off splashes. Washing with large amounts of plain [[water]] (most labs have a safety shower or eye-wash) and removal of contaminated clothing are required, and immediate [[hospital]] treatment for large splashes. This is particularly important if the phenol is mixed with [[chloroform]] (a commonly-used mixture in molecular biology for [[DNA]] & [[RNA]] purification from proteins).
Phenol is also used in the preparation of [[cosmetics]] including [[sunscreen]]s<ref>{{cite journal | author = A. Svobodová*, J. Psotová, and D. Walterová | title = Natural Phenolics in the Prevention of UV-Induced Skin Damage. A Review | year = 2003 | journal = [[Biomed. Papers]] | volume = 147 | issue = 2 | pages = 137–145}}</ref>, [[hair dyes]], and [[skin lightening]] preparations<ref>DeSelms, R. H.; ''[http://www.para-gen.com/paragen/publications.htm UV-Active Phenol Ester Compounds]''; Enigen Science Publishing: Washington, DC, 2008.</ref>. Compounds containing phenol moieties can be used to prevent [[ultraviolet light]]-induced damage to hair and skin due to the UV-absorbing properties of the aromatic ring of the phenol. These compounds also act as [[free radical scavengers]] and can be used to prevent [[premature aging]] and [[cancer]] caused by [[oxidative stress]].
It is also used in [[cosmetic surgery]] as an [[exfoliant]], to remove layers of dead skin. It is also used in phenolization, a surgical procedure used to treat an [[ingrown nail]], in which it is applied to the toe to prevent regrowth of [[nail (anatomy)|nails]]. 5% Phenol is sometimes injected near a sensory nerve in order to temporarily (up to a year) stop it transmitting impulses in some intractable cases of [[chronic pain| chronic]] [[neuropathy|neuropathic]] pain.
===Second World War===
Injections of phenol have occasionally been used as a means of rapid [[execution]]. In particular, phenol was used as a means of extermination by the [[Nazi]]s before and during the [[Second World War]]. Originally used by the [[Nazi]]s in the 1930s as part of its [[euthanasia]] program, phenol, cheap and easy to make and quickly effective, became the injectable drug of choice through the last days of the War. Although [[Zyklon-B]] pellets were used in the gas chambers to exterminate large groups of people, the [[Nazi]]s learned that extermination of smaller groups was more economical via injection of each victim one at a time with phenol instead. Phenol injections were given to thousands of people in [[Nazi concentration camps|concentration camps]], especially at [[Auschwitz-Birkenau]]. Injections were administered by [[medical doctor]]s, their [[physician assistant|assistant]]s, or sometimes prisoner doctors; such injections were originally given [[Intravenous therapy|intravenous]]ly, more commonly in the [[arm]], but injection directly into the [[heart]], so as to induce nearly instant [[death]], was later preferred <ref name="carbolic">{{cite web | publisher = Johannes Kepler University, 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 | accessdate=2006-09-29}}</ref>
. One of the most famous inmates at Auschwitz to be executed by carbolic acid injection was [[St. Maximilian Kolbe]], a Catholic priest who volunteered to undergo three weeks of starvation and dehydration in the place of another inmate and who was finally injected with carbolic acid so that the Nazis could make more room in their holding cells. <ref name="carbolic" />
==Hydrothermal chemistry==
Under laboratory conditions mimicking [[hydrothermal circulation]] (water, 200 °C, 1.9 GPa), phenol is found to form from [[sodium hydrogen carbonate]] and [[iron]] powder (1.8% [[chemical yield]])<ref>''Hydrothermal Reactions from Sodium Hydrogen Carbonate to Phenol'' Ge Tian, Hongming Yuan, Ying Mu, Chao He, and Shouhua Feng Org. Lett.; '''2007'''; 9(10) pp 2019 - 2021; (Letter) DOI: 10.1021/ol070597o</ref>. This discovery made in 2007 may be relevant to the [[origin of life]] question as phenol is a fragment of the biomolecule [[tyrosine]]. However, as tyrosine is known to result directly from hydroxylation of [[phenylalanine]] in modern biological systems,<ref>[http://web.indstate.edu/thcme/mwking/amino-acid-metabolism.html#tyrosine THE Medical Biochemistry Page<!-- Bot generated title -->]</ref> the implications of prebiotic phenol are questionable at best.
==See also==
* [[Bamberger rearrangement]]
* [[Claisen rearrangement]]
* [[Cresols]]
* [[Fries rearrangement]]
==References==
{{reflist}}
==External links==
* [http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc00/icsc0070.htm International Chemical Safety Card 0070]
* [http://www.jtbaker.com/msds/englishhtml/p1949.htm Phenol Material Safety Data Sheet]
* [http://www.npi.gov.au/database/substance-info/profiles/70.html National Pollutant Inventory - Phenol Fact Sheet]
* [http://www.cdc.gov/niosh/npg/npgd0493.html NIOSH Pocket Guide to Chemical Hazards]
* [http://www-cie.iarc.fr/htdocs/monographs/vol71/027-phenol.html IARC Monograph: "Phenol"]
* [http://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}}
[[Category:Phenols|*]]
[[Category:Antiseptics]]
[[Category:Hazardous air pollutants]]
[[Category:IARC Group 3 carcinogens]]
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