o-Cresol

o-Cresol
Names
Systematic IUPAC name
2-Methylphenol[1]
Other names
2-Hydroxytoluene,
2-Cresol,
o-Cresylic acid,
1-Hydroxy-2-methylbenzene,
Identifiers
3DMet B00313
506917
95-48-7 Yes
ChEBI CHEBI:28054 
ChEMBL ChEMBL46931 
ChemSpider 13835772 
EC number 202-423-8
101619
Jmol-3D images Image
KEGG C01542 
MeSH 2-Cresol
PubChem 335
RTECS number GO6300000
UNII YW84DH5I7U 
UN number 2076, 3455
Properties
Molecular formula
 C7H8O
Molar mass 108.14 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
1.5353
Viscosity 35.06 cP (at 45 °C)
Thermochemistry
Specific
heat capacity (C)
 154.56 J K−1 mol−1
165.44 J K−1 mol−1
Std enthalpy of
formation (ΔfHo298)
 -204.3 kJ mol−1
Std enthalpy of
combustion (ΔcHo298)
 -3.6936 MJ mol−1
Hazards
MSDS External MSDS
EU Index 604-004-00-9
EU classification T C
R-phrases R24/25, R34
S-phrases (S1/2), S36/37/39, S45
NFPA 704
Flammability code 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 fuel Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
2
3
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)[2]
1350 mg/kg (rat, oral)
US health exposure limits (NIOSH):
TWA 5 ppm (22 mg/m3) [skin][2]
TWA 2.3 ppm (10 mg/m3)[2]
250 ppm[2]
Related compounds
Related phenols
 m-cresol, p-cresol, phenol
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

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, 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 plant food.[4]

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 propylene. 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, for example, at lower levels over longer times. The acute LD50 for oral ingestion by mice is 344 mg/kg.[3]

External links

References

  1. ↑ "2-Cresol - PubChem Public Chemical Database". The PubChem Project. USA: National Center for Biotechnology Information.
  2. ↑ 2.0 2.1 2.2 2.3 "NIOSH Pocket Guide to Chemical Hazards #0154". National Institute for Occupational Safety and Health (NIOSH).
  3. ↑ 3.0 3.1 3.2 3.3 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)