Xylenols are organic compounds with the formula (CH3)2C6H3OH. They are volatile colorless solids or oily liquids. They are derivatives of phenol with twomethyl groups at various positions relative to thehydroxyl group. Sixisomers exist, of which2,6-xylenol with both methyl groups in anortho position with respect to the hydroxyl group is the most important. The namexylenol is aportmanteau of the wordsxylene andphenol.
2,4-Dimethylphenol together with other xylenols and many other compounds are traditionally extracted fromcoal tar, the volatile materials obtained in the production of coke from coal. These residue contains a few percent by weight of xylenols as well as cresols and phenol. The main xylenols in such tar are the 3,5-, 2,4, and 2,3- isomers. 2,6-Xylenol is produced bymethylation of phenol usingmethanol in the presence of metal oxide catalysts:[1]
Typically, xylenols alsoethylphenols, which have very similar physical properties.[2]
The physical properties of the six isomeric xylenols are similar.
| Isomer | 2,6-Xylenol | 2,5-Xylenol | 2,4-Xylenol | 2,3-Xylenol | 3,4-Xylenol | 3,5-Xylenol |
| Structure |  |  |  |  |  |  |
| CAS | 576-26-1 | 95-87-4 | 105-67-9 | 526-75-0 | 95-65-8 | 108-68-9 |
| Mp °C | 43-45 | 63 - 65 | 22-23 | 70-73 | 62 - 68 | 61-64 |
| Bp °C | 203 | 212 | 211-212 | 217 | 227 | 222 |
| pKa[3] | 10.59 | 10.22 | 10.45 | 10.50 | 10.32 | 10.15 |
| Density g/mL | 0.971 | 1.011 |
Together withcresols and cresylic acid, xylenols are an important class of phenolics with great industrial importance. They are used in the manufacture ofantioxidants.Xylenol orange is aredox indicator built on a xylenol skeleton. 2,6-Xylenol is amonomer forpoly(p-phenylene oxide) (PEO) engineering resins through carbon-oxygenoxidative coupling.