O-Cresol

o-Cresol
Systematic name 2-Methylphenol[1]
Other names 2-Hydroxytoluene
Identifiers
CAS number	95-48-7 Y
PubChem	335
ChemSpider	13835772 N
UNII	YW84DH5I7U N
EC number	202-423-8
UN number	2076, 3455
KEGG	C01542 N
MeSH	2-Cresol
ChEBI	CHEBI:28054 N
ChEMBL	CHEMBL46931 N
RTECS number	GO6300000
Beilstein Reference	506917
Gmelin Reference	101619
3DMet	B00313
Jmol-3D images	Image 1
SMILES Cc1ccccc1O
InChI InChI=1S/C7H8O/c1-6-4-2-3-5-7(6)8/h2-5,8H,1H3 N Key: QWVGKYWNOKOFNN-UHFFFAOYSA-N N
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
Solubility in water	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
Refractive index (nD)	1.5353
Viscosity	35.06 cP (at 45 °C)
Thermochemistry
Std enthalpy of formation ΔfHo298	-204.3 kJ mol-1
Std enthalpy of combustion ΔcHo298	-3.6936 MJ mol-1
Standard molar entropy So298	165.44 J K-1 mol-1
Specific heat capacity, C	154.56 J K-1 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	2 3 0
Flash point	81 °C; 178 °F; 354 K
Autoignition temperature	598.9 °C; 1,110.0 °F; 872.0 K
LD50	1350 mg/kg (rat, oral)
Related compounds
Related phenols	m-cresol, p-cresol, phenol
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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.^[2]

Natural occurrences

o-Cresol is one of the chemical compounds found in castoreum. This compound is gathered from the beaver plant food.^[3]

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.^[2]

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.^[2]

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.^[2]

External links

• o-CRESOL (ICSC)
• Environmental Science - SMILES Examples Notations
• CDC - NIOSH Pocket Guide to Chemical Hazards

References