P-Cresol

{{Short description|Chemical compound}} {{DISPLAYTITLE:''p''-Cresol}} {{use dmy dates|date=November 2022}} {{chembox | verifiedrevid = 477506207 | Name = ''p''-Cresol | ImageFile = Para-cresol-horizontal-2D-skeletal.png | ImageName = Skeletal formula of ''p''-cresol | ImageFile1 = p-cresol-spaceFilling.png | ImageSize1 = 150px | ImageName1 = 3D model of ''p''-cresol | ImageFile2 = P-Cresol.jpg | PIN = 4-Methylphenol | SystematicName = 4-Methylbenzenol | OtherNames = 4-Cresol<br/>''p''-Cresol<br />4-Hydroxytoluene<br/>''p''-Cresylic acid<br/>1-Hydroxy-4-methylbenzene | Section1 = {{Chembox Identifiers | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 106-44-5 | ChEMBL_Ref = {{ebicite|correct|EBI}} | ChEMBL = 16645 | RTECS = GO6475000 | DrugBank_Ref = {{drugbankcite|correct|drugbank}} | DrugBank = DB01688 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 1MXY2UM8NV | SMILES = Cc1ccc(O)cc1 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 17847 | KEGG_Ref = {{keggcite|correct|kegg}} | KEGG = C01468 | ChemSpiderID = 13839082 | PubChem = 2879 | EC_number = 203-398-6 | Beilstein = 1305151 | Gmelin = 2779 | InChI = 1/C7H8O/c1-6-2-4-7(8)5-3-6/h2-5,8H,1H3 | InChIKey = IWDCLRJOBJJRNH-UHFFFAOYAN | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C7H8O/c1-6-2-4-7(8)5-3-6/h2-5,8H,1H3 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = IWDCLRJOBJJRNH-UHFFFAOYSA-N }} | Section2 = {{Chembox Properties | Appearance = colorless prismatic crystals | Formula = C₇H₈O | MolarMass = 108.13 | BoilingPtC = 201.8 | MeltingPtC = 35.5 | Density = 1.0347 g/ml | RefractIndex = 1.5395 | Solubility = 2.4 g/100 ml at 40&nbsp;°C<br>5.3 g/100 ml at 100&nbsp;°C | Solubility1 = [[miscible]] | Solvent1 = ethanol | Solubility2 = [[miscible]] | Solvent2 = diethyl ether | VaporPressure = 0.11 mmHg (25&nbsp;°C)<ref name=PGCH/> | MagSus = {{val|-72.1e-6|u=cm³/mol}} }} | Section7 = {{Chembox Hazards | ExternalSDS = [https://web.archive.org/web/20221104172905/https://www.emdmillipore.com/US/en/product/msds/MDA_CHEM-805223 External MSDS] | FlashPtC = 86.1 | MainHazards = May be fatal if swallowed, inhaled, or absorbed through skin. | NFPA-H = 3 | NFPA-F = 1 | NFPA-R = 0 | GHSPictograms = {{GHS05}}{{GHS06}}{{GHS08}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|201|311|314|351|370|372|373|401|412}} | PPhrases = {{P-phrases|201|202|260|264|270|273|280|281|301+310|301+330+331|302+352|303+361+353|304+340|305+351+338|307+311|308+313|310|312|314|321|322|330|361|363|405|501}} | PEL = TWA 5 ppm (22 mg/m³) [skin]<ref name=PGCH>{{PGCH|0156}}</ref> | ExploLimits = 1.1%–?<ref name=PGCH/> | IDLH = 250 ppm<ref name=PGCH/> | LD50 = 207 mg/kg (oral, rat, 1969)<br/>1800 mg/kg (oral, rat, 1944)<br/>344 mg/kg (oral, mouse)<ref>{{IDLH|cresol|Cresol (o, m, p isomers)}}</ref> | REL = TWA 2.3 ppm (10 mg/m³)<ref name=PGCH/> }} | Section8 = {{Chembox Related | OtherFunction_label = [[phenol]]s | OtherFunction = [[O-Cresol|''o''-cresol]], [[M-Cresol|''m''-cresol]], [[phenol]] }} }}

'''''para''-Cresol''', also '''4-methylphenol''', is an [[organic compound]] with the formula CH₃C₆H₄(OH). It is a colourless solid that is widely used intermediate in the production of other chemicals. It is a derivative of [[phenol]] and is an isomer of [[O-Cresol|''o''-cresol]] and [[M-Cresol|''m''-cresol]].<ref name=Ullmann>{{Ullmann|doi=10.1002/14356007.a08_025 |title=Cresols and Xylenols |year=2000 |last1=Fiege |first1=Helmut | name-list-style = vanc |isbn=3-527-30673-0}}</ref>

==Production== Together with many other compounds, ''p''-cresol is conventionally extracted from [[coal tar]], the volatilized materials obtained in the roasting of [[coal]] to produce [[coke (fuel)|coke]]. This residue contains a few percent by weight of [[phenol]] and [[cresol]]s. Industrially, ''p''-cresol is currently prepared mainly by a two-step route beginning with the [[sulfonation]] of [[toluene]]:<ref>{{cite journal|doi=10.15227/orgsyn.003.0037|title=''p''-Cresol|journal=Organic Syntheses|volume=3|pages=37|year=1923|author=W. W. Hartman}}</ref> :CH₃C₆H₅ + [[sulfuric acid|H₂SO₄]] → CH₃C₆H₄SO₃H + H₂O [[Base (chemistry)|Basic]] hydrolysis of the [[sulfonate]] salt gives the sodium salt of the cresol: :CH₃C₆H₄SO₃H + 2 NaOH → CH₃C₆H₄OH + Na₂SO₃ + H₂O Other methods for the production of ''p''-cresol include chlorination of toluene followed by hydrolysis. In the cymene-cresol process, toluene is [[alkylated]] with [[propene]] to give [[p-Cymene|''p''-cymene]], which can be oxidatively dealkylated in a manner similar to the [[cumene process]].<ref name=Ullmann/>

== Applications == ''p''-Cresol is consumed mainly in the production of [[antioxidant]]s, such as [[butylated hydroxytoluene]] (BHT). The monoalkylated derivatives undergo coupling to give an extensive family of diphenol antioxidants. These antioxidants are valued because they are relatively low in toxicity and nonstaining.<ref name=Ullmann/><ref>{{Cite web |date=April 2005 |title=meta- and para-Cresols |url=https://inchem.org/documents/sids/sids/m-p-cresols.pdf |url-status=dead |archive-url=https://web.archive.org/web/20171208161609/https://inchem.org/documents/sids/sids/m-p-cresols.pdf |archive-date=2017-12-08 |access-date=2022-11-04 |website=[[International Programme on Chemical Safety]] (IPCS INCHEM)}}</ref><ref name="hazmap">{{Cite web |title=p-Cresol - Hazardous Agents |url=https://haz-map.com/Agents/16387?#:~:text=used,materials |access-date=2022-11-04 |website=[[Haz-Map]]: Information on Hazardous Chemicals and Occupational Diseases}}</ref>

== Natural occurrences == === In humans === ''p''-Cresol is produced by [[bacterial fermentation]] of [[protein]] in the human [[large intestine]]. It is excreted in feces and urine,<ref>{{cite journal | vauthors = Hamer HM, De Preter V, Windey K, Verbeke K | title = Functional analysis of colonic bacterial metabolism: relevant to health? | journal = American Journal of Physiology. Gastrointestinal and Liver Physiology | volume = 302 | issue = 1 | pages = G1-9 | date = January 2012 | pmid = 22016433 | pmc = 3345969 | doi = 10.1152/ajpgi.00048.2011}}</ref> and is a component of human [[sweat]] that attracts female [[mosquito]]es.<ref>{{cite journal | vauthors = Hallem EA, Nicole Fox A, Zwiebel LJ, Carlson JR | title = Olfaction: mosquito receptor for human-sweat odorant | journal = Nature | volume = 427 | issue = 6971 | pages = 212–213 | date = January 2004 | pmid = 14724626 | doi = 10.1038/427212a | bibcode = 2004Natur.427..212H| s2cid = 4419658 }}</ref><ref>{{cite journal | vauthors = Linley JR | title = Laboratory tests of the effects of ''p''-cresol and 4-methylcyclohexanol on oviposition by three species of ''Toxorhynchites'' mosquitoes | journal = Medical and Veterinary Entomology | volume = 3 | issue = 4 | pages = 347–52 | date = October 1989 | pmid = 2577519 | doi = 10.1111/j.1365-2915.1989.tb00241.x| s2cid = 1641506 }}</ref>

''p''-Cresol is a constituent of [[tobacco smoke]].<ref>{{cite journal | vauthors = Talhout R, Schulz T, Florek E, van Benthem J, Wester P, Opperhuizen A | title = Hazardous compounds in tobacco smoke | journal = International Journal of Environmental Research and Public Health | volume = 8 | issue = 2 | pages = 613–28 | date = February 2011 | pmid = 21556207 | pmc = 3084482 | doi = 10.3390/ijerph8020613| doi-access = free }}</ref>

=== In other species === ''p''-Cresol is a major component in [[pig]] odor.<ref>{{Cite web | first = Brendan | last = Borrell | date = 5 March 2009 | url = http://www.sciam.com/article.cfm?id=why-study-pig-odor | title = Why study pig odor? | work = Scientific American | access-date = 9 March 2009 | archive-date = 20 March 2021 | archive-url = https://web.archive.org/web/20210320042122/https://www.scientificamerican.com/article/why-study-pig-odor/ | url-status = live }}</ref> Temporal glands secretion examination showed the presence of phenol and ''p''-cresol during [[musth]] in male [[elephant]]s.<ref>{{cite journal | vauthors = Rasmussen LE, Perrin TE | title = Physiological correlates of musth: lipid metabolites and chemical composition of exudates | journal = Physiology & Behavior | volume = 67 | issue = 4 | pages = 539–49 | date = October 1999 | pmid = 10549891 | doi = 10.1016/S0031-9384(99)00114-6| s2cid = 21368454 }}</ref><ref>{{cite journal |title=Musth in elephants |first1=Deepa |last1=Ananth | name-list-style = vanc|journal=Zoos' Print Journal |volume=15 |issue=5 |pages=259–62 |doi=10.11609/jott.zpj.14.4.259-62|date=May 2000 |doi-access=free}}</ref> It is one of the very few compounds to attract the [[Euglossini|orchid bee]] ''[[Euglossa cyanura]]'' and has been used to capture and study the species.<ref>{{cite journal |vauthors=Williams NH, Whitten WM |date=June 1983 |title=Orchid Floral Fragrances and Male Euglossine Bees: Methods and Advances in the Last Sesquidecade |journal=Biological Bulletin |volume=164 |issue=3 |pages=355–95 |jstor=1541248 |doi=10.2307/1541248 |url=https://www.biodiversitylibrary.org/part/35261 |access-date=2021-11-10 |archive-date=2020-06-05 |archive-url=https://web.archive.org/web/20200605121541/https://www.biodiversitylibrary.org/part/35261 |url-status=live }}</ref> ''p''-Cresol is a component found in [[horse]] urine during [[estrus]] that can elicit the [[Flehmen response]].<ref>{{cite journal | vauthors = Būda V, Mozūraitis R, Kutra J, Borg-Karlson AK | title = ''p''-Cresol: a sex pheromone component identified from the estrous urine of mares | journal = Journal of Chemical Ecology | volume = 38 | issue = 7 | pages = 811–3 | date = July 2012 | pmid = 22592336 | doi = 10.1007/s10886-012-0138-2| s2cid = 14558317 }}</ref>

''p''-Cresol is found in numerous [[essential oils]] - typically in trace quantities where its intense odour imparts an animalic character.<ref>{{cite web |title=para-cresol|url=https://scentsandflavors.com/database/9dbb4f60-e83f-443a-a0c6-f23c3e02fbce |website=scentsandflavors.com |access-date=15 May 2026}}</ref>

== References == {{Reflist}}

{{DEFAULTSORT:Cresol, p-}} [[Category:Cresols]] [[Category:4-Tolyl compounds]]