View source for Cresol

{{short description|Group of chemical compounds}}
{{distinguish|creosol}}
{| align="right" border="1" cellspacing="0" cellpadding="3" style="margin: 0 0 0 0.5em; background: #FFFFFF; border-collapse: collapse; border-color: #C0C090;"
! {{Chemical datatable header}}  align="center" colspan="4" | Isomers of Cresol<ref>[http://www.inchem.org/documents/icsc/icsc/eics0030.htm o-CRESOL (ICSC)]</ref><ref>[http://www.inchem.org/documents/icsc/icsc/eics0646.htm m-CRESOL (ICSC)]</ref><ref>[http://www.inchem.org/documents/icsc/icsc/eics0031.htm p-CRESOL (ICSC)]</ref><ref>{{Cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/o-cresol#section=Odor-Threshold|title=o-cresol|last=Pubchem|website=pubchem.ncbi.nlm.nih.gov|language=en|access-date=2018-01-16}}</ref>
|-
| [[Skeletal formula]]
| [[file:O-Kresol.svg|90px|center]]
| [[file:M-Kresol.svg|90px|center]]
| [[file:P-Kresol.svg|45px|center]]
|-
| [[Ball-and-stick model]]
| [[Image:Ortho-cresol-3D-balls.png|100px]]
| [[Image:Meta-cresol-3D-balls.png|100px]]
| [[Image:Para-cresol-3D-balls.png|100px]]
|-
! {{Chemical datatable header}} align="center" colspan="4" | General
|-
| Common name
| '''[[o-cresol|''o''-cresol]]'''
| '''[[m-cresol|''m''-cresol]]'''
| '''[[p-cresol|''p''-creso]]l'''
|-
| [[Preferred IUPAC name]]
| 2-methylphenol
| 3-methylphenol
| 4-methylphenol
|-
| [[Chemical nomenclature#Systematic name|Systematic name]]
| 2-methylbenzenol
| 3-methylbenzenol
| 4-methylbenzenol
|-
| Other names
| ''ortho''-cresol<br />2-hydroxytoluene
| ''meta''-cresol<br />3-hydroxytoluene
| ''para''-cresol<br />4-hydroxytoluene
|-
| [[Chemical formula|Molecular formula]]
| align="center" colspan="4" |  C<sub>7</sub>H<sub>8</sub>O
|-
| [[Simplified molecular input line entry specification|SMILES]]
| oc1c(C)cccc1
| oc1cc(C)ccc1
| oc1ccc(C)cc1
|-
| [[Molar mass]]
| align="center" colspan="4" |  108.14 g/mol
|-
| Appearance at room<br /> temperature and pressure
|  colorless crystals
|  thicker liquid
|  greasy-looking solid
|-
|rowspan="2" | [[CAS registry number|CAS number]]
| <nowiki>[95-48-7]</nowiki>
| <nowiki>[108-39-4]</nowiki>
| <nowiki>[106-44-5]</nowiki>
|-
| align="center" colspan="3" | mixture of cresols (tricresol): <nowiki>[1319-77-3]</nowiki>
|-
! {{Chemical datatable header}} align="center" colspan="4" | Properties
|-
| [[Density]] and [[Phase (matter)|phase]]
| 1.05 g/cm<sup>3</sup>, solid
| 1.03 g/cm<sup>3</sup>, liquid
| 1.02 g/cm<sup>3</sup>, liquid
|-
| [[Soluble|Solubility]] in [[Water (molecule)|pure water]]<br /> at 20−25&nbsp;°C
| 2.5 g/100 ml
| 2.4 g/100 ml
| 1.9 g/100 ml
|-
| align="center" colspan="4" | soluble in strongly [[alkaline]] water
|-
<!-- | Other solvents e.g. [[ethanol]], [[acetone]] -->
<!-- | solubility info on other solvents -->
<!-- |- -->
| [[Melting point]]
|  29.8&nbsp;°C (303.0 K)
|  11.8&nbsp;°C (285.0 K)
|  35.5&nbsp;°C (309.7 K)
|-
| [[Boiling point]]
| 191.0&nbsp;°C (464.2 K)
| 202.0&nbsp;°C (475.2 K)
| 201.9&nbsp;°C (475.1 K)
|-
| [[Acid dissociation constant|Acidity]] (p''K''<sub>a</sub>) <!-- omit if not an acid or a base.  If several values, be clear -->
| 10.287
| 10.09
| 10.26
|-
| [[Viscosity]]
| solid at 25&nbsp;°C
| ? c[[Poise (unit)|P]] at 25&nbsp;°C
| solid at 25&nbsp;°C
|-

! {{Chemical datatable header}} align="center" colspan="4" | Structure
|-
| [[Dipole#Molecular dipoles|Dipole moment]]
| 1.35 [[Debye|D]]
| 1.61 [[Debye|D]]
| 1.58 [[Debye|D]]
|-

! {{Chemical datatable header}} align="center" colspan="4" | Hazards <!--  Summary only- MSDS entry provides more complete information -->
|-
| [[Safety data sheet|SDS]]
| <!--[[Cresol chemdata supplement#Material Safety Data Sheet|External MSDS]]  please replace with proper link-->
|
|
|-
| Main [[Worker safety and health|hazard]]s
| align="center" colspan="4" |  [[flammable]], ingestion and inhalation toxicity hazard
|-
| [[Flash point]]
| 81&nbsp;°C c.c.
| 86&nbsp;°C
| 86&nbsp;°C c.c.
|-
| [[GHS pictograms]]
| align="center" colspan="4" |  {{GHS05}}{{GHS06}}
|-
| [[RTECS]] number
| GO6300000
| GO6125000
| GO6475000
|-
! {{Chemical datatable header}} align="center" colspan="4" | Related compounds
|-
| Related [[phenols]]
| colspan="3"| [[xylenol]]s
|-
| Related compounds
| colspan="3"| [[bromocresol green]], [[cresol red]]
|-
| {{Chemical datatable header}} align="center" colspan="4" | <small>Except where noted otherwise, data are given for<br /> materials in their [[standard state|standard state (at 25&nbsp;°C, 100 kPa)]]<br />[[wikipedia:Chemical infobox|Infobox disclaimer and references]]</small>
|-
|}

'''Cresols''' (also known as '''hydroxytoluene''', '''toluenol''', '''benzol''' or '''cresylic acid''') are a group of [[aromatic]] [[organic compound]]s. They are widely-occurring [[phenols]] (sometimes called ''phenolics'') which may be either natural or manufactured. They are also categorized as '''[[methyl group|methyl]] [[phenol]]s'''. Cresols commonly occur as either solids or liquids because their [[melting point]]s are generally close to room temperature. Like other types of phenols, they are slowly [[oxidation|oxidized]] by exposure to [[air]], and the resulting impurities often give the samples a yellow to brownish red tint. Cresols have an [[odor]] characteristic to that of other simple phenols, reminiscent to some of a "[[coal tar]]" smell. The name "cresol" is an adduct of phenol and their traditional source, [[creosote]].

==Structure and production==
In its [[chemical structure]], a [[molecule]] of cresol has a [[methyl group]] substituted onto the ring of phenol. There are three forms ([[isomers]]) of cresol: ''ortho''-cresol ([[o-Cresol|''o''-cresol]]), ''meta''-cresol ([[m-Cresol|''m''-cresol]]), and ''para''-cresol ([[p-Cresol|''p''-cresol]]). These forms occur separately or as a mixture, which can also be called cresol or more specifically, '''tricresol'''.{{citation needed|date=December 2017}} About half of the world's supply of cresols are extracted from coal tar. The rest is produced by [[hydrolysis]] of [[chlorotoluene]]s or the related sulfonates.  Another method entails methylation of phenol with methanol over a solid acid catalyst, often comprising magnesium oxide or alumina. Temperatures above 300&nbsp;°C are typical. [[Anisole]] converts to cresols under these conditions.<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><ref name=Ullmann/>

Another [[isomer]] of cresol is called [[Benzyl alcohol]], or ''alpha''-cresol (α-cresol). Benzyl alcohol has a hydroxy group inside a methyl group on the [[benzene]] ring.

== Applications ==
Cresols are precursors or synthetic intermediates to other compounds and materials, including plastics, pesticides, pharmaceuticals, and dyes.<ref name=Ullmann>Helmut Fiegein "Cresols and Xylenols" in Ullmann's Encyclopedia of Industrial Chemistry" 2007; Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a08_025}}</ref>

For cresol bactericides or disinfectants the mechanism of action is due to the destruction of bacterial [[cell membranes]].<ref name="judis62">{{cite journal |doi=10.1002/jps.2600510317|title=Studies on the Mechanism of Action of Phenolic Disinfectants I|year=1962|last1=Judis|first1=Joseph|journal=Journal of Pharmaceutical Sciences|volume=51|issue=3|pages=261–265|pmid=14452711}}</ref><ref name="dboc">{{cite news |title=IDENTIFICATION Name Cresol |url=https://go.drugbank.com/drugs/DB11143 |publisher=DrugBank Online |date=12 June 2020}}</ref>

Most recently, cresols have been used to create a breakthrough in manufacturing [[carbon nanotubes]] at scale that are separated and not twisted, without additional chemicals that change the surface properties of the nanotubes.<ref>{{cite web |title=Making carbon nanotubes as usable as common plastics: Researchers discover that cresols disperse carbon nanotubes at unprecedentedly high concentrations |url=http://www.sciencedaily.com/releases/2018/05/180515162801.htm |publisher=ScienceDaily, Northwestern University |url-status=live |archive-url=https://web.archive.org/web/20180516060704/http://www.sciencedaily.com/releases/2018/05/180515162801.htm |archive-date=2018-05-16 |date=15 May 2018}}</ref><ref>{{cite journal |last1=Chiou |first1=Kevin |last2=Byun |first2=Segi |last3=Kim |first3=Jaemyung |last4=Huang |first4=Jiaxing |title=Additive-free carbon nanotube dispersions, pastes, gels, and doughs in cresols |journal=Proceedings of the National Academy of Sciences |date=29 May 2018 |volume=115 |issue=22 |pages=5703–5708 |doi=10.1073/pnas.1800298115|pmid=29760075 |pmc=5984515 |bibcode=2018PNAS..115.5703C |doi-access=free }} {{open access}}</ref>

===Commercial examples===
* [[Creolin]], a 19th-century disinfectant.
* [[Carbolic soap]], 19th-century.
* The original [[Lysol]] formulation, essentially a water solution of carbolic soap.<ref name="LysolCresolReference">{{cite book
|url=http://www.gutenberg.org/files/21724/21724-h/21724-h.htm
|title=THE HANDBOOK OF SOAP MANUFACTURE no
|year=1908
|publisher=SCOTT, GREENWOOD & SON
|last=SIMMONS|first=W.H.}}</ref> "Lysol" has been used as a [[generic trademark]] to refer to such a cresol soap solution and remains used as such in some professional settings. The CAS number is 12772-68-8.

=== Derivatives ===
Derivatives of ''p''-cresol include:
* [[Butylated hydroxytoluene]], a common [[antioxidant]]

Derivatives of ''o''-cresol include:
* [[Indo-1]], a popular calcium indicator
* [[MCPA]], (4-chloro-2-methylphenoxy)acetic acid
* [[MCPB]], 4-(4-chloro-2-methylphenoxy)butanoic acid
* [[Mecoprop]], (''RS'')-2-(4-chloro-2-methylphenoxy)propanoic acid
* the [[amine]] [[atomoxetine]], (3''R'')-''N''-methyl-3-(2-methylphenoxy)-3-phenylpropan-1-amine
* the [[diol]] [[mephenesin]], 3-(2-methylphenoxy)propane-1,2-diol

Derivatives of ''m''-cresol include:
* [[Amylmetacresol]], an [[antiseptic]]
* [[Bevantolol]], (''RS'')-[2-(3,4-dimethoxyphenyl)ethyl] [2-hydroxy-3-(3-methylphenoxy)propyl]amine
* [[Bromocresol green]]
* [[Bupranolol]], a non-selective [[beta blocker]]
* [[Chloro-m-cresol|Chloro-''m''-cresol]] which is used as a household disinfectant
* [[Tolimidone]], 5-(3-methylphenoxy)pyrimidin-2(1''H'')-one

==Health effects==
When cresols are inhaled, ingested, or applied to the [[skin]], they can be very harmful. Effects observed in people include [[irritation]] and burning of skin, [[eye]]s, [[mouth]], and [[throat]]; abdominal pain and vomiting; [[heart]] damage; [[anemia]]; [[liver]] and [[kidney]] damage; facial paralysis; [[coma]]; and [[death]].

Breathing high levels of cresols for a short time results in irritation of the [[human nose|nose]] and throat. Aside from these effects, very little is known about the effects of breathing cresols, for example, at lower levels over longer times.

Ingesting high levels results in kidney problems, mouth and throat burns, abdominal pain, vomiting, and effects on the [[blood]] and [[nervous system]].

Skin contact with high levels of cresols can burn the skin and damage the kidneys, liver, blood, [[brain]], and [[lung]]s.

Short-term and long-term studies with animals have shown similar effects from exposure to cresols. No human or animal studies have shown harmful effects from cresols on reproduction.

It is not known what the effects are from long-term ingestion or skin contact with low levels of cresols.

The [[Occupational Safety and Health Administration]] has set a [[permissible exposure limit]] at 5 ppm (22&nbsp;mg/m<sup>3</sup>) over an eight-hour time-weighted average, while the [[National Institute for Occupational Safety and Health]] [[recommended exposure limit|recommends a limit]] of  2.3 ppm (10&nbsp;mg/m<sup>3</sup>).<ref>[https://www.cdc.gov/niosh/idlh/cresol.html Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs) - Cresol (o, m, p isomers)]</ref>

==See also==
* [[Dihydroxytoluene]]
* [[Trihydroxytoluene]]

==References==
{{reflist}}

{{Authority control}}

[[Category:Antiseptics]]
[[Category:Cresols| ]]
[[Category:Multiple compounds, tabular|C]]