Xylene: Structure, Formula, Uses & Risk

Xylene is a colourless liquid-vapour that is part of the aromatic Hydrocarbon group. It is produced by the thermal reforming of certain cycloalkane petroleum distillates. The Isomers of Xylene are meta-xylene, ortho-xylene, and para-xylene. The chemical formula for Xylene is C₈H₁₀ or (C₆H₄) (CH₃)₂. Xylene is commonly used as a high powered motor and aviation fuel mixture, solvent, and chemical intermediate. 

Key Terms: Xylene, Isomers, Dimethyl benzene, organic compound, Hydrocarbon, Cycloalkane, Petroleum Distillate

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What is Xylene?

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Xylene is a colourless aromatic hydrocarbon. It has three isomers namely meta-xylene, ortho-xylene, and para-xylene. The fourth Isomer is Ethyl Benzene. The chemical Xylene was named after Xylong, the Greek word for wood as it was found in the crude wood spirit. The formula for Xylene is C₈H₁₀ or (C₆H₄) (CH₃)₂.

Xylene is not a solvent in water but it can float on top if combined with dense water, however, it is miscible with several other organic liquids. Other names for Xylene are Methyl Toluene, Xylol, Dimethyl Benzene, and Mixed Xylenes.

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Structure of Xylene

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• The structure of Xylene is a mix of two methyl groups attached to a six-carbon ring. 
• Xylene is not one but three Isomeric Dimethyl benzene which has the same chemical formula but different molecular structures. 
• The three of the Isomers that are officially chosen, ortho (o), meta (m), and para (p) differ structurally only in the location of the methyl groups. 
• The obtained Xylol contains 40-60% of m-xylene, 20% of o-xylene (approx.), 20% of p-xylene, and 6-20% of ethyl benzene

Structure of Xylene

• Fractional distillation removes meta and para isomers, which have the same boiling point, from less explosive ortho Isomer. 
• Upon cooling of the mixture of both the Isomers (meta and para), they crystallize in a pure form. 
• The meta isomer (principal component of the remaining liquid) is then purified by taking advantage of its solubility in a mixture of hydrofluoric acid and boron trifluoride.

Read More: Alkanes

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Properties of Xylene

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The chemical properties of different isomers of Xylene are given below. 

Dimethylbenzene (o- Xylene)

• Density and Phase: 0.88g/mL, liquid
• Boiling Point: 144^oC
• Viscosity: 0.812 cP at 20^oC
• Flashpoint: 17^oC

Dimythylbenzene (m-Xylene)

• Density and Phase: 0.86g/Ml, liquid
• Boiling Point: 139^oC
• Viscosity: 0.62 cP at 30^oC
• Flashpoint: 25^oC

Dimythylbenzene (p-Xylene)

• Density and Phase: 0.86g/Ml, liquid
• Boiling Point: 138^oC
• Viscosity: 0.34 cP at 30^oC
• Flashpoint: 25^oC

Xylene’s melting point can differ from -47.87^oC for m-Xylene to 13.26^oC for p-Xylene.

Read More: Alkenes

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Uses of Xylene

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• One of the most important uses of Xylene is in Medicine, particularly in microscopic examination of tissues. It is used in the process of staining the tissues.
• Xylene is very commonly used as a paint solvent because it is excellent at removing old paint on a variety of surfaces. 
• Xylene is also effective in removing greasy stains, resins, enamels, and glue.
• Xylene is also used in the form of raw material in the manufacturing of fibres, films, and dyes.
• Xylene is used as a lubricant in the form of motor oil or brake fluid.
• Xylene is used as a cleaning agent in various fields, such as dentistry and electronics to the petroleum industry (p-Xylene).
• Xylene is also used in cosmetic products for removing excessive ear wax.
• Xylene can be used as a pesticide and disinfectant.

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Exposure Risks of Xylene

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Xylene serves as a useful source to multiple industries, but it comes with several risks too. 

Health Risks of Xylene Exposure

More than adults the health risk of Xylene exposure is greatly seen among children. 

• Exposure to Xylene can occur via inhalation, ingestion, and eye or skin contact. 
• It is metabolized to Methylhypric acid mainly in the liver by oxidation of methyl groups and combination with glycerin, which is excreted through the urinal gland. 
• A small amount is excreted unchanged with exhalation.
• The measure of severity can be both acute and also chronic. Individuals react differently to different exposures.
• The primary risk of Xylene is through Inhalation which directly affects the nervous system. 
• Xylene is known to be a slow depressant which means it slows the central nervous system, leading to headaches, irritability, nausea, dizziness even fainting, short-term memory loss, and vomiting. 
• The level of intake may also cause visual impairment.
• Xylene, if came in contact with the skin, can dissolve its natural protective oils. 
• Damaged skin may result in a greater risk of absorption of chemicals causing the skin to be dry or feel irritation because of the exposure. The Xylene in liquid form can also cause a painful burning sensation on the skin
• Xylene in contact with the eye can damage the cornea.

Corrosive Effects of Xylene

• Corrosion is a chemical reaction that breaks down new compounds through the process of oxidation. 
• Being great solvents, Xylene dissolves non-polar organic compounds and generally don’t react chemically with other substances in normal conditions. Therefore, it is not considered Harmful. 
• Xylene can be destructive if converted to acids like monocarboxylic acids (toluic acids), and dicarboxylic acids (phthalic acids) when oxidized.

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Things to Remember

• Xylene is an aromatic organic chemical compound also known as dimethyl benzene or Xylol.
• Xylene is a colorless, sweet-smelling flammable, nonviscous, toxic liquid.
• They are derived from the substitution of two hydrogen atoms with the methyl groups in a benzene ring
• Each molecule has a benzene ring and two of the methyl group linked to it.
• IUPAC Name: o-Isomer: 1,2 dimethylbenzene, m-Isomer: 1,3 dimethylbenzene, p-Isomer: 1,4 dimethylbenzene

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Previous Year Questions

• Which of the following compounds undergoes nitration more readily? [AMUEE 2012]
• The effective electrophile in aromatic sulphonation is?[NEET 2003]
• Identity Z in the sequence of reactions… [KCET 2016]
• Some meta-directing substituents in aromatic substitution are given… [AMUEE 2007]
• Correct order of stability is? [NEET 2001]
• Which one of these is not compatible with arenes? [NEET 2011]

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