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Isomers of Cresol^[1]^[2]^[3]
Skeletal formula
Ball-and-stick model
General
Common name	o-cresol	m-cresol	p-cresol
Systematic name	2-methylphenol	3-methylphenol	4-methylphenol
Other names	ortho-cresol	meta-cresol	para-cresol
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]
CAS number	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, liquid
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 (pK_a)	10.26	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.
R/S statement	R24/25-R34 ((S1/2)-)S36/37/S39-S45
RTECS number
Related compounds
Related phenols	xylenols
Related compounds	bromo cresol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Cresols (also hydroxytoluene) are organic compounds which are methylphenols. They are a widely occurring natural and manufactured group of aromatic organic compounds, which are categorized as phenols (sometimes called phenolics). Depending on the temperature, cresols can be solid or liquid because they have melting points not far from room temperature. Like other types of phenols, they are slowly oxidized by long exposure to air and the impurities often give cresols a yellowish 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 reflects their structure, being phenols, 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), meta-cresol (m-cresol), and para-cresol (p-cresol). These forms occur separately or as a mixture, which can also be called cresol or more specifically, tricresol. About half of the world's supply of cresols are extracted from coal tar.^[4] The rest is produced synthetically, by methylation of phenol or hydrolysis of chlorotoluenes.^[5]

Applications

Cresols are precursors or synthetic intermediates to other compounds and materials, including plastics, pesticides, pharmaceuticals, and dyes.^[5]

Commercial examples

Derivatives of p-cresol include:

Bupranolol, a non-selective beta blocker
Butylated hydroxytoluene, a common antioxidant
Indo-1, a popular calcium indicator

Derivatives of o-cresol include:

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, (3R)-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
Chloro-m-cresol which is used as a household disinfectant
Tolimidone, 5-(3-methylphenoxy)pyrimidin-2(1H)-one

Health effects

Most exposures to cresols are at very low levels that are not harmful. When cresols are inhaled, ingested, or applied to the skin at very high levels, they can be very harmful. Effects observed in people include irritation and burning of skin, eyes, 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 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 lungs.

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 mg/m³) over an eight hour time-weighted average, while the National Institute for Occupational Safety and Health recommends a limit of 2.3 ppm (10 mg/m³).^[6]

References

^ o-CRESOL (ICSC)
^ m-CRESOL (ICSC)
^ p-CRESOL (ICSC)
^ http://medical-dictionary.thefreedictionary.com/tricresol. 18 July, 2013.
^ ^a ^b Helmut Fiegein "Cresols and Xylenols" in Ullmann's Encyclopedia of Industrial Chemistry" 2007; Wiley-VCH, Weinheim. doi:10.1002/14356007.a08_025
^ Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs) - Cresol (o, m, p isomers)

English Journal

Novel polymer anchored Cr(III) Schiff base complexes: Synthesis, characterization and antimicrobial properties.

Selvi C, Nartop D.SourceDepartment of Chemistry, Faculty of Arts and Science, Nevşehir University, 50300, 2000 Evler Mh. Zübeyde Hanım Cd., Nevşehir, Turkey.
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.Spectrochim Acta A Mol Biomol Spectrosc.2012 Sep;95:165-71. Epub 2012 May 3.
New polymer-bound Schiff bases and Cr(III) complexes have been synthesized by the reaction of 4-benzyloxybenzaldehyde, polymer-bound with 2-aminophenol, 2-amino-4-chlorophenol and 2-amino-4-methylphenol. The structure of polymeric-Schiff bases and their Cr(III) complexes have been characterized by e
PMID 22622060

Molecular structure, spectroscopic studies (FTIR, FT-Raman and NMR) and HOMO-LUMO analysis of 6-chloro-o-cresol and 4-chloro-3-methyl phenol by density functional theoretical study.

Krishnakumar V, Kumar M, Prabavathi N, Mathammal R.SourceDepartment of Physics, Periyar University, Salem 636 011, India.
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.Spectrochim Acta A Mol Biomol Spectrosc.2012 Jun 6;97C:144-154. [Epub ahead of print]
In this work, the experimental and theoretical vibrational spectra of 6-chloro-o-cresol (COC) and 4-chloro-3-methylphenol (CMP) have been studied. FTIR and FT-Raman spectra of the title compounds in the solid phase are recorded in the region 4000-400cm(-1) and 4000-50cm(-1), respectively. The struct
PMID 22750683

Japanese Journal

二核化大環状配位子錯体によって創られる多様な分子構造

宮里裕二
日本結晶学会誌 52(5), 246-249, 2010-10-31
… Dinuclear metal complex with phenol based dinucleating macrocyclic ligand (L2-) derived from the [2+2] condensation of 2,6-diformyl-4-methylphenol and 1,3-diaminopropane can act as ‘complex as metal’, since axial position of the dinuclear complex is available for accepting donation from ‘another ligand’. …
NAID 10027673065

Differences in Flavor Characteristics of Coffee Drinks Originating from Thermal Sterilization Process

MURAKAMI Kazuya,AKIYAMA Masayuki,SUMI Masahiro,IKEDA Michio,IWATSUKI Keiji,NISHIMURA Osamu,KUMAZAWA Kenji
Food science and technology research 16(2), 99-110, 2010-03-01
… graphy/olfactometry analysis revealed three odorants (2-furanemethanethiol, 3-(methylthio)propanal, and 3-mercapto-3-methylbutyl formate) whose flavor dilution (FD) factors decreased in the unsterilized, UHT-sterilized, and retort sterilized products in this order and eight odorants (2-((methylthio)methyl)furan, 3-mercapto-3-methyl-1-butanol, 3-methylbutyric acid, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 4-methylphenol, and three unidentified odorants) whose FD factors increased in the unsterilized, UHT-sterilized, and retort sterilized products in this …
NAID 10027496250