# Cresol

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Not to be confused with [creosol](/source/Creosol).

Isomers of Cresol[1][2][3][4] Skeletal formula Ball-and-stick model General Common name o-cresol m-cresol p-cresol Preferred IUPAC name 2-methylphenol 3-methylphenol 4-methylphenol Systematic name 2-methylbenzenol 3-methylbenzenol 4-methylbenzenol Other names ortho-cresol 2-hydroxytoluene meta-cresol 3-hydroxytoluene para-cresol 4-hydroxytoluene Molecular formula C7H8O SMILES oc1c(C)cccc1 oc1cc(C)ccc1 oc1ccc(C)cc1 Molar mass 108.14 g/mol Appearance at room temperature and pressure colorless crystals thicker liquid greasy-looking solid CAS number [95-48-7] [108-39-4] [106-44-5] [105-22-1] mixture of cresols (tricresol): [1319-77-3] Properties Density and phase 1.05 g/cm3, solid 1.03 g/cm3, liquid 1.02 g/cm3, solid Solubility in pure water at 20−25 °C 2.5 g/100 ml 2.4 g/100 ml 1.9 g/100 ml soluble in strongly alkaline water Melting point 29.8 °C (303.0 K) 11.8 °C (285.0 K) 35.5 °C (309.7 K) Boiling point 191.0 °C (464.2 K) 202.0 °C (475.2 K) 201.9 °C (475.1 K) Acidity (pKa) 10.287 10.09 10.26 Viscosity solid at 25 °C ? cP at 25 °C solid at 25 °C Structure Dipole moment 1.35 D 1.61 D 1.58 D Hazards SDS Main hazards flammable, ingestion and inhalation toxicity hazard Flash point 81 °C c.c. 86 °C 86 °C c.c. GHS pictograms RTECS number GO6300000 GO6125000 GO6475000 Related compounds Related phenols xylenols Related compounds bromocresol green, cresol red Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

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

## Structure and production

In its [chemical structure](/source/Chemical_structure), a [molecule](/source/Molecule) of cresol has a [methyl group](/source/Methyl_group) substituted onto the ring of phenol. There are three forms ([isomers](/source/Isomers)) of cresol: *ortho*-cresol ([*o*-cresol](/source/O-Cresol)), *meta*-cresol ([*m*-cresol](/source/M-Cresol)), and *para*-cresol ([*p*-cresol](/source/P-Cresol)). These forms occur separately or as a mixture, which can also be called cresol or more specifically, **tricresol**.[citation needed] About half of the world's supply of cresols are extracted from coal tar. The rest is produced by [hydrolysis](/source/Hydrolysis) of [chlorotoluenes](/source/Chlorotoluene) 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 °C are typical. [Anisole](/source/Anisole) converts to cresols under these conditions.[5][6]

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

## Applications

Cresols are precursors or synthetic intermediates to other compounds and materials, including plastics, pesticides, pharmaceuticals, and dyes.[6]

For cresol bactericides or disinfectants the mechanism of action is due to the destruction of bacterial [cell membranes](/source/Cell_membranes).[7][8]

Most recently, cresols have been used to create a breakthrough in manufacturing [carbon nanotubes](/source/Carbon_nanotubes) at scale that are separated and not twisted, without additional chemicals that change the surface properties of the nanotubes.[9][10]

### Commercial examples

- [Creolin](/source/Creolin), a 19th-century disinfectant.
- [Carbolic soap](/source/Carbolic_soap), 19th-century.
- The original [Lysol](/source/Lysol) formulation, essentially a water solution of carbolic soap.[11] "Lysol" has been used as a [generic trademark](/source/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](/source/Butylated_hydroxytoluene), a common [antioxidant](/source/Antioxidant)

Derivatives of *o*-cresol include:

- [Indo-1](/source/Indo-1), a popular calcium indicator
- [MCPA](/source/MCPA), (4-chloro-2-methylphenoxy)acetic acid
- [MCPB](/source/MCPB), 4-(4-chloro-2-methylphenoxy)butanoic acid
- [Mecoprop](/source/Mecoprop), (*RS*)-2-(4-chloro-2-methylphenoxy)propanoic acid
- the [amine](/source/Amine) [atomoxetine](/source/Atomoxetine), (3*R*)-*N*-methyl-3-(2-methylphenoxy)-3-phenylpropan-1-amine
- the [diol](/source/Diol) [mephenesin](/source/Mephenesin), 3-(2-methylphenoxy)propane-1,2-diol

Derivatives of *m*-cresol include:

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

## Health effects

When cresols are inhaled, ingested, or applied to the [skin](/source/Skin), they can be very harmful. Effects observed in people include [irritation](/source/Irritation) and burning of skin, [eyes](/source/Eye), [mouth](/source/Mouth), and [throat](/source/Throat); abdominal pain and vomiting; [heart](/source/Heart) damage; [anemia](/source/Anemia); [liver](/source/Liver) and [kidney](/source/Kidney) damage; facial paralysis; [coma](/source/Coma); and [death](/source/Death).

Breathing high levels of cresols for a short time results in irritation of the [nose](/source/Human_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](/source/Blood) and [nervous system](/source/Nervous_system).

Skin contact with high levels of cresols can burn the skin and damage the kidneys, liver, blood, [brain](/source/Brain), and [lungs](/source/Lung).

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](/source/Occupational_Safety_and_Health_Administration) has set a [permissible exposure limit](/source/Permissible_exposure_limit) at 5 ppm (22 mg/m3) over an eight-hour time-weighted average, while the [National Institute for Occupational Safety and Health](/source/National_Institute_for_Occupational_Safety_and_Health) [recommends a limit](/source/Recommended_exposure_limit) of 2.3 ppm (10 mg/m3).[12]

## See also

- [Dihydroxytoluene](/source/Dihydroxytoluene)
- [Trihydroxytoluene](/source/Trihydroxytoluene)

## References

1. [o-CRESOL (ICSC)](http://www.inchem.org/documents/icsc/icsc/eics0030.htm)

1. [m-CRESOL (ICSC)](http://www.inchem.org/documents/icsc/icsc/eics0646.htm)

1. [p-CRESOL (ICSC)](http://www.inchem.org/documents/icsc/icsc/eics0031.htm)

1. Pubchem. ["o-cresol"](https://pubchem.ncbi.nlm.nih.gov/compound/o-cresol#section=Odor-Threshold). *pubchem.ncbi.nlm.nih.gov*. Retrieved 2018-01-16.

1. W. W. Hartman (1923). "*p*-Cresol". *Organic Syntheses*. **3**: 37. [doi:10.15227/orgsyn.003.0037](https://doi.org/10.15227/orgsyn.003.0037)

1. Helmut Fiegein "Cresols and Xylenols" in Ullmann's Encyclopedia of Industrial Chemistry" 2007; Wiley-VCH, Weinheim. [doi:10.1002/14356007.a08_025](https://doi.org/10.1002/14356007.a08_025)

1. Judis, Joseph (1962). "Studies on the Mechanism of Action of Phenolic Disinfectants I". *Journal of Pharmaceutical Sciences*. **51** (3): 261–265. [doi:10.1002/jps.2600510317](https://doi.org/10.1002/jps.2600510317). [PMID 14452711](https://pubmed.ncbi.nlm.nih.gov/14452711)

1. ["IDENTIFICATION Name Cresol"](https://go.drugbank.com/drugs/DB11143). DrugBank Online. 12 June 2020.

1. ["Making carbon nanotubes as usable as common plastics: Researchers discover that cresols disperse carbon nanotubes at unprecedentedly high concentrations"](http://www.sciencedaily.com/releases/2018/05/180515162801.htm). ScienceDaily, Northwestern University. 15 May 2018. [Archived](https://web.archive.org/web/20180516060704/http://www.sciencedaily.com/releases/2018/05/180515162801.htm) 2018-05-16 at the Wayback Machine.

1. Chiou, Kevin; Byun, Segi; Kim, Jaemyung; Huang, Jiaxing (29 May 2018). "Additive-free carbon nanotube dispersions, pastes, gels, and doughs in cresols". *Proceedings of the National Academy of Sciences*. **115** (22): 5703–5708. [Bibcode:2018PNAS..115.5703C](https://ui.adsabs.harvard.edu/abs/2018PNAS..115.5703C). [doi:10.1073/pnas.1800298115](https://doi.org/10.1073/pnas.1800298115). [PMC 5984515](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5984515). [PMID 29760075](https://pubmed.ncbi.nlm.nih.gov/29760075)

1. SIMMONS, W.H. (1908). [*THE HANDBOOK OF SOAP MANUFACTURE no*](http://www.gutenberg.org/files/21724/21724-h/21724-h.htm). SCOTT, GREENWOOD & SON.

1. [Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs) - Cresol (o, m, p isomers)](https://www.cdc.gov/niosh/idlh/cresol.html)

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Adapted from the Wikipedia article [Cresol](https://en.wikipedia.org/wiki/Cresol) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Cresol?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.