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| ImageFileL1 = O-Kresol.svg
| ImageFileL1 = O-Kresol.svg
| ImageFileL1_Ref = {{chemboximage|correct|??}}
| ImageFileL1_Ref = {{chemboximage|correct|??}}
| ImageNameL1 = Kekulé, skeletal formula of o-cresol with some implicit hydrogens shown
| ImageNameL1 = Kekulé, skeletal formula of ''o''-cresol with some implicit hydrogens shown
| ImageFileR1 = Ortho-cresol-3D-vdW.png
| ImageFileR1 = Ortho-cresol-3D-vdW.png
| ImageFileR1_Ref = {{chemboximage|correct|??}}
| ImageFileR1_Ref = {{chemboximage|correct|??}}
| ImageNameR1 = Spacefill model of o-cresol
| ImageNameR1 = Spacefill model of ''o''-cresol
| PIN = 2-Methylphenol
| PIN = 2-Methylphenol
| SystematicName = 2-Methylbenzenol
| SystematicName = 2-Methylbenzenol
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| Odor = sweet, phenolic odor
| Odor = sweet, phenolic odor
| C=7 | H=8 | O=1
| C=7 | H=8 | O=1
| Density = 1.0465 g cm<sup>−3</sup>
| Density = 1.0465 g&nbsp;cm<sup>−3</sup>
| Solubility = 31 g dm<sup>−3</sup> (at 40 °C)
| Solubility = 31 g&nbsp;dm<sup>−3</sup> (at 40&nbsp;°C)
| Solvent1 = ethanol
| Solvent1 = ethanol
| Solubility1 = Miscible (at 30 °C)
| Solubility1 = Miscible (at 30&nbsp;°C)
| Solvent2 = diethyl ether
| Solvent2 = diethyl ether
| Solubility2 = Miscible (at 30 °C)
| Solubility2 = Miscible (at 30&nbsp;°C)
| SolubleOther = soluble in [[chloroform]], [[diethyl ether|ether]], [[carbon tetrachloride|CCl<sub>4</sub>]]
| SolubleOther = soluble in [[chloroform]], [[diethyl ether|ether]], [[carbon tetrachloride|CCl<sub>4</sub>]]
| MeltingPtK = 304
| MeltingPtK = 304
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| RefractIndex = 1.5353
| RefractIndex = 1.5353
| LogP = 1.962
| LogP = 1.962
| VaporPressure = 40 Pa (at 20 °C)
| VaporPressure = 40 Pa (at 20&nbsp;°C)
| pKa = 10.316
| pKa = 10.316
| pKb = 3.681
| pKb = 3.681
| Viscosity = 35.06 cP (at 45 °C)
| Viscosity = 35.06 cP (at 45&nbsp;°C)
| MagSus = -72.9·10<sup>−6</sup> cm<sup>3</sup>/mol
| MagSus = {{val|-72.9e-6|u=cm<sup>3</sup>/mol}}
}}
}}
|Section3={{Chembox Thermochemistry
|Section3={{Chembox Thermochemistry
| DeltaHf = -204.3 kJ mol<sup>−1</sup>
| DeltaHf = −204.3 kJ&nbsp;mol<sup>−1</sup>
| DeltaHc = -3.6936 MJ mol<sup>−1</sup>
| DeltaHc = −3.6936 MJ&nbsp;mol<sup>−1</sup>
| Entropy = 165.44 J K<sup>−1</sup> mol<sup>−1</sup>
| Entropy = 165.44 J&nbsp;K<sup>−1</sup>&nbsp;mol<sup>−1</sup>
| HeatCapacity = 154.56 J K<sup>−1</sup> mol<sup>−1</sup>
| HeatCapacity = 154.56 J&nbsp;K<sup>−1</sup>&nbsp;mol<sup>−1</sup>
}}
}}
|Section4={{Chembox Hazards
|Section4={{Chembox Hazards
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| LD50 = 1350 mg/kg (rat, oral)<br/>121 mg/kg (rat, oral)<br/>344 mg/kg (mouse, oral)<ref>{{IDLH|cresol|Cresol (o, m, p isomers)}}</ref>
| LD50 = 1350 mg/kg (rat, oral)<br/>121 mg/kg (rat, oral)<br/>344 mg/kg (mouse, oral)<ref>{{IDLH|cresol|Cresol (o, m, p isomers)}}</ref>
| PEL = TWA 5 ppm (22 mg/m<sup>3</sup>) [skin]<ref name=PGCH>{{PGCH|0154}}</ref>
| PEL = TWA 5 ppm (22 mg/m<sup>3</sup>) [skin]<ref name=PGCH>{{PGCH|0154}}</ref>
| ExploLimits = 1.4%-? (148°C)<ref name=PGCH/>
| ExploLimits = 1.4%–? (148&nbsp;°C)<ref name=PGCH/>
| IDLH = 250 ppm<ref name=PGCH/>
| IDLH = 250 ppm<ref name=PGCH/>
| REL = TWA 2.3 ppm (10 mg/m<sup>3</sup>)<ref name=PGCH/>
| REL = TWA 2.3 ppm (10 mg/m<sup>3</sup>)<ref name=PGCH/>
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== Natural occurrences ==
== Natural occurrences ==
''o''-Cresol is one of the chemical compounds found in [[castoreum]]. This compound is gathered from the beaver's castor glands and found in the white cedar consumed by the beaver.<ref>The Beaver: Its Life and Impact. Dietland Muller-Schwarze, 2003, page 43 ([https://books.google.com/books?id=HZ5WjXB5Pr8C&lpg=PA39&ots=WYwTmWi-yJ&dq=Castoreum%20beekeeping&lr&hl=en&pg=PA43#v=onepage&q=Castoreum%20beekeeping&f=false book at google books])</ref>
''o''-Cresol is one of the chemical compounds found in [[castoreum]]. This compound is gathered from the beaver's castor glands and found in the white cedar consumed by the [[beaver]].<ref>The Beaver: Its Life and Impact. Dietland Muller-Schwarze, 2003, page 43 ([https://books.google.com/books?id=HZ5WjXB5Pr8C&lpg=PA39&ots=WYwTmWi-yJ&dq=Castoreum%20beekeeping&lr&hl=en&pg=PA43#v=onepage&q=Castoreum%20beekeeping&f=false book at google books])</ref>


''o''-Cresol is a constituent of [[tobacco smoke]].<ref>{{cite journal|last1=Talhout|first1=Reinskje|last2=Schulz|first2=Thomas|last3=Florek|first3=Ewa|last4=Van Benthem|first4=Jan|last5=Wester|first5=Piet|last6=Opperhuizen|first6=Antoon|title=Hazardous Compounds in Tobacco Smoke|journal=International Journal of Environmental Research and Public Health|volume=8|issue=12|year=2011|pages=613–628|issn=1660-4601|doi=10.3390/ijerph8020613|pmid=21556207|pmc=3084482}}</ref>
''o''-Cresol is a constituent of [[tobacco smoke]].<ref>{{cite journal|last1=Talhout|first1=Reinskje|last2=Schulz|first2=Thomas|last3=Florek|first3=Ewa|last4=Van Benthem|first4=Jan|last5=Wester|first5=Piet|last6=Opperhuizen|first6=Antoon|title=Hazardous Compounds in Tobacco Smoke|journal=International Journal of Environmental Research and Public Health|volume=8|issue=12|year=2011|pages=613–628|issn=1660-4601|doi=10.3390/ijerph8020613|pmid=21556207|pmc=3084482}}</ref>


== Production ==
== Production ==
Together with many other compounds, o-cresol is traditionally extracted from [[coal tar]], the volatile materials obtained in the production of coke from coal. A similar source material is petroleum residues. These residue contains a few percent by weight of phenol and isomeric cresols. In addition to the materials derived from these natural sources, about two thirds of the Western world's supply is produced by [[methylation]] of phenol using methanol. The [[alkylation]] is catalysed by metal oxides:
Together with many other compounds, ''o''-cresol is traditionally extracted from [[coal tar]], the volatile materials obtained in the production of [[coke]] from [[coal]]. A similar source material is petroleum residues. These residue contains a few percent by weight of [[phenol]] and isomeric [[cresol]]s. In addition to the materials derived from these natural sources, about two thirds of the Western world's supply is produced by [[methylation]] of phenol using [[methanol]]. The [[alkylation]] is catalysed by metal oxides:
:C<sub>6</sub>H<sub>5</sub>OH + CH<sub>3</sub>OH → CH<sub>3</sub>C<sub>6</sub>H<sub>4</sub>OH + H<sub>2</sub>O
:C<sub>6</sub>H<sub>5</sub>OH + CH<sub>3</sub>OH → CH<sub>3</sub>C<sub>6</sub>H<sub>4</sub>OH + H<sub>2</sub>O
Over-methylation gives [[xylenol]]. Many other production methods have been examined, including oxidative decarboxylation of [[salicylic acid]], oxygenation of [[toluene]], and hydrolysis of [[2-chlorotoluene]].<ref name=Ullmann/>
Over-methylation gives [[xylenol]]. Many other production methods have been examined, including oxidative decarboxylation of [[salicylic acid]], oxygenation of [[toluene]], and hydrolysis of [[2-chlorotoluene]].<ref name=Ullmann/>


== Applications ==
== Applications ==
''o''-Cresol is mainly used as a precursor to other compounds. Chlorination and etherification gives members of a commercially important [[herbicide]]s, such as [[2-methyl-4-chlorophenoxyacetic acid]] (MCPA). Nitration gives [[dinitrocresol]], a popular herbicide. [[Kolbe–Schmitt reaction|Kolbe–Schmitt carboxylation]] gives [[o-cresotinic acid|''o''-cresotinic acid]], a pharmaceutical intermediate. [[Carvacrol]], essence of oregano, is derived by alkylation of o-cresol with [[propene]]. The muscle relaxant [[mephenesin]] is an ether derived from ''o''-cresol.<ref name=Ullmann/>
''o''-Cresol is mainly used as a precursor to other compounds. Chlorination and etherification gives members of a commercially important [[herbicide]]s, such as [[2-methyl-4-chlorophenoxyacetic acid]] (MCPA). Nitration gives [[dinitrocresol]], a popular herbicide. [[Kolbe–Schmitt reaction|Kolbe–Schmitt carboxylation]] gives [[o-cresotinic acid|''o''-cresotinic acid]], a pharmaceutical intermediate. [[Carvacrol]], essence of oregano, is derived by alkylation of ''o''-cresol with [[propene]]. The muscle relaxant [[mephenesin]] is an ether derived from ''o''-cresol.<ref name=Ullmann/>


== Health effects ==
== Health effects ==
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== External links ==
== External links ==
* [http://www.inchem.org/documents/icsc/icsc/eics0030.htm o-CRESOL (ICSC)]
* [http://www.inchem.org/documents/icsc/icsc/eics0030.htm ''o''-CRESOL (ICSC)]
* [http://www.syrres.com/esc/smiles_ex_notations.htm Environmental Science - SMILES Examples Notations]
* [http://www.syrres.com/esc/smiles_ex_notations.htm Environmental Science - SMILES Examples Notations]
* [https://www.cdc.gov/niosh/npg/npgd0154.html CDC - NIOSH Pocket Guide to Chemical Hazards]
* [https://www.cdc.gov/niosh/npg/npgd0154.html CDC - NIOSH Pocket Guide to Chemical Hazards]

Revision as of 13:47, 14 January 2021

o-Cresol
Kekulé, skeletal formula of o-cresol with some implicit hydrogens shown
Kekulé, skeletal formula of o-cresol with some implicit hydrogens shown
Spacefill model of o-cresol
Spacefill model of o-cresol
Names
Preferred IUPAC name
2-Methylphenol
Systematic IUPAC name
2-Methylbenzenol
Other names
2-Cresol
o-Cresol
ortho-Cresol
2-Hydroxytoluene
o-Cresylic acid
1-Hydroxy-2-methylbenzene
Identifiers
3D model (JSmol)
506917
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.204 Edit this at Wikidata
EC Number
  • 202-423-8
101619
KEGG
MeSH 2-Cresol
RTECS number
  • GO6300000
UNII
UN number 2076, 3455
  • InChI=1S/C7H8O/c1-6-4-2-3-5-7(6)8/h2-5,8H,1H3 checkY
    Key: QWVGKYWNOKOFNN-UHFFFAOYSA-N ☒N
  • Cc1ccccc1O
Properties
C7H8O
Molar mass 108.140 g·mol−1
Appearance Colorless to white crystals
Odor sweet, phenolic odor
Density 1.0465 g cm−3
Melting point 31 °C; 88 °F; 304 K
Boiling point 191 °C; 376 °F; 464 K
31 g dm−3 (at 40 °C)
Solubility soluble in chloroform, ether, CCl4
Solubility in ethanol Miscible (at 30 °C)
Solubility in diethyl ether Miscible (at 30 °C)
log P 1.962
Vapor pressure 40 Pa (at 20 °C)
Acidity (pKa) 10.316
Basicity (pKb) 3.681
−72.9×10−6 cm3/mol
1.5353
Viscosity 35.06 cP (at 45 °C)
Thermochemistry
154.56 J K−1 mol−1
165.44 J K−1 mol−1
−204.3 kJ mol−1
−3.6936 MJ mol−1
Hazards
GHS labelling:
GHS05: CorrosiveGHS06: Toxic
Danger
H301, H311, H314
P260, P264, P270, P280, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P322, P330, P361, P363, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
2
0
Flash point 81 °C (178 °F; 354 K)
598.9 °C (1,110.0 °F; 872.0 K)
Explosive limits 1.4%–? (148 °C)[1]
Lethal dose or concentration (LD, LC):
1350 mg/kg (rat, oral)
121 mg/kg (rat, oral)
344 mg/kg (mouse, oral)[2]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 5 ppm (22 mg/m3) [skin][1]
REL (Recommended)
 TWA 2.3 ppm (10 mg/m3)[1]
IDLH (Immediate danger)
 250 ppm[1]
Safety data sheet (SDS) External MSDS
Related compounds
Related phenols
 m-cresol, p-cresol, phenol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

ortho-Cresol, also 2-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 p-cresol and m-cresol.[3]

Natural occurrences

o-Cresol is one of the chemical compounds found in castoreum. This compound is gathered from the beaver's castor glands and found in the white cedar consumed by the beaver.[4]

o-Cresol is a constituent of tobacco smoke.[5]

Production

Together with many other compounds, o-cresol is traditionally extracted from coal tar, the volatile materials obtained in the production of coke from coal. A similar source material is petroleum residues. These residue contains a few percent by weight of phenol and isomeric cresols. In addition to the materials derived from these natural sources, about two thirds of the Western world's supply is produced by methylation of phenol using methanol. The alkylation is catalysed by metal oxides:

C6H5OH + CH3OH → CH3C6H4OH + H2O

Over-methylation gives xylenol. Many other production methods have been examined, including oxidative decarboxylation of salicylic acid, oxygenation of toluene, and hydrolysis of 2-chlorotoluene.[3]

Applications

o-Cresol is mainly used as a precursor to other compounds. Chlorination and etherification gives members of a commercially important herbicides, such as 2-methyl-4-chlorophenoxyacetic acid (MCPA). Nitration gives dinitrocresol, a popular herbicide. Kolbe–Schmitt carboxylation gives o-cresotinic acid, a pharmaceutical intermediate. Carvacrol, essence of oregano, is derived by alkylation of o-cresol with propene. The muscle relaxant mephenesin is an ether derived from o-cresol.[3]

Health effects

Most exposures to cresols are at very low levels that are not harmful although, like phenols, cresols are skin irritants. When cresols are breathed, ingested, or applied to the skin at very high levels, they can be harmful. 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 at lower levels over longer times. The acute LD50 for oral ingestion by mice is 344 mg/kg.[3]

References

  1. ^ a b c d NIOSH Pocket Guide to Chemical Hazards. "#0154". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ "Cresol (o, m, p isomers)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  3. ^ a b c d Helmut Fiegein "Cresols and Xylenols" in Ullmann's Encyclopedia of Industrial Chemistry" 2007; Wiley-VCH, Weinheim. doi:10.1002/14356007.a08_025
  4. ^ The Beaver: Its Life and Impact. Dietland Muller-Schwarze, 2003, page 43 (book at google books)
  5. ^ Talhout, Reinskje; Schulz, Thomas; Florek, Ewa; Van Benthem, Jan; Wester, Piet; Opperhuizen, Antoon (2011). "Hazardous Compounds in Tobacco Smoke". International Journal of Environmental Research and Public Health. 8 (12): 613–628. doi:10.3390/ijerph8020613. ISSN 1660-4601. PMC 3084482. PMID 21556207.{{cite journal}}: CS1 maint: unflagged free DOI (link)
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