Xylenols are organic compounds with the formula (CH₃)₂C₆H₃OH. They are volatile colorless solids or oily liquids. They are derivatives of phenol with two

methyl In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many ...

groups at various positions relative to the

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

group. Six

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

s exist, of which 2,6-xylenol with both methyl groups in an ortho position with respect to the hydroxyl group is the most important. The name ''xylenol'' is a

portmanteau A portmanteau word, or portmanteau (, ) is a blend of wordsxylene In organic chemistry, xylene or xylol (; IUPAC name: dimethylbenzene) are any of three organic compounds with the formula . They are derived from the substitution of two hydrogen atoms with methyl groups in a benzene ring; which hydrogens are sub ...

and

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it req ...

. 2,4-Dimethylphenol together with other xylenols and many other compounds are traditionally extracted from

coal tar Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. It is a type of creosote. It has both medical and industrial uses. Medicinally it is a topical medication applied to skin to treat psoriasi ...

, 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 by

methylation In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These t ...

of phenol using

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...

in the presence of metal oxide catalysts:Helmut Fiegein "Cresols and Xylenols" in ''Ullmann's Encyclopedia of Industrial Chemistry'', 2007; Wiley-VCH, Weinheim. :C₆H₅OH + 2 CH₃OH → (CH₃)₂C₆H₃OH + 2 H₂O Typically, xylenols also

ethylphenol Ethylphenol may refer to: * 2-Ethylphenol * 3-Ethylphenol * 4-Ethylphenol * Ethyl phenyl ether Ethyl phenyl ether (or phenetole) is an organic compound that belongs to a class of compounds called ethers. Ethyl phenyl ether has the same properti ...

s, which have very similar physical properties.

Properties

The physical properties of the six isomeric xylenols are similar.

Uses

Together with

cresol Cresols (also hydroxytoluene or cresylic acid) are a group of aromatic organic compounds. They are widely-occurring phenols (sometimes called ''phenolics'') which may be either natural or manufactured. They are also categorized as methylphenols. ...

s and cresylic acid, xylenols are an important class of phenolics with great industrial importance. They are used in the manufacture of

antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...

Xylenol orange Xylenol orange is an organic reagent, most commonly used as a tetrasodium salt as an indicator for metal titrations. When used for metal titrations, it will appear red in the titrand and become yellow once it reaches its endpoint. Historically, ...

is a

redox indicator A redox indicator (also called an oxidation-reduction indicator) is an indicator which undergoes a definite color change at a specific electrode potential. The requirement for fast and reversible color change means that the oxidation-reduction e ...

built on a xylenol skeleton. 2,6-Xylenol is a

monomer In chemistry, a monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization. Classification Mo ...

for

poly(p-phenylene oxide) Poly(''p''-phenylene oxide) (PPO), poly(''p''-phenylene ether) (PPE), often referred to simply as polyphenylene oxide, is a high-temperature thermoplastic. It is rarely used in its pure form due to difficulties in processing. It is mainly used as ...

(PEO) engineering resins through carbon-oxygen

oxidative coupling Oxidative coupling in chemistry is a coupling reaction of two molecular entities through an oxidative process. Usually oxidative couplings are catalysed by a transition metal complex like in classical cross-coupling reactions, although the underly ...

References

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External links

Datasheet 2,6 isomer

Datasheet 2,5 isomer

Datasheet 2,4 isomer

Datasheet 2,3 isomer

Datasheet 3,4 isomer

Datasheet 3,5 isomer
Alkylphenols

Properties

Uses

See also

References

External links