Toluene is an organic chemical compound belonging to the family of aromatic hydrocarbons, with the chemical formula C₆H₅CH₃ or C₇H₈.
It is a colorless, volatile, and highly flammable liquid with an odor similar to paint thinners.
Due to its unique properties, toluene is one of the most widely used industrial chemicals — serving as a powerful solvent and a raw material in the paint, adhesive, polymer, pharmaceutical, and fuel industries.

Structure of Toluene

Toluene consists of a benzene ring attached to a single methyl group (–CH₃).
This structure imparts both aromatic stability and alkyl reactivity, allowing it to participate in various chemical reactions.

• Molecular Formula: C₇H₈

• Chemical Structure: Benzene ring with one methyl substituent

• IUPAC Name: Methylbenzene

• CAS Number: 108-88-3

Physical and Chemical Properties of Toluene

• Appearance: Clear, colorless, volatile liquid with a sweet, pungent odor

• Molecular Weight: 92.14 g/mol

• Density (20°C): 0.866–0.870 g/cm³

• Boiling Point: 110.6°C

• Melting Point: −95°C

• Vapor Pressure (20°C): 28–30 mmHg

• Water Solubility: Slight (~0.52 g/L at 25°C)

• Solubility in Organic Solvents: Completely miscible with acetone, ethanol, ether, and most organic solvents

• Flammability: Highly flammable (flash point ≈ 4°C)

Advantages of Toluene

• Excellent solvency power for a wide range of organic compounds

• Cost-effective and readily available on an industrial scale

• High compatibility with diverse chemical processes

• Essential role as an intermediate in the production of numerous industrial and pharmaceutical materials

Disadvantages and Limitations

• Moderate toxicity to humans (especially with prolonged inhalation or skin contact)

• Direct effects on the central nervous system (dizziness, headache, drowsiness)

• Environmental hazard in case of accidental spills or improper disposal

• High flammability requiring strict safety and storage measures

Applications of Toluene

• Paints, Varnishes, and Thinners: As a major solvent component

• Printing and Ink Industry: Used to dissolve resins and pigments

• Polymer Manufacturing: In the production of polyurethanes, nylon, and synthetic resins

• Chemical Synthesis:

  • Benzene (via dealkylation)

  • Trinitrotoluene (TNT)

  • Benzoic acid and its derivatives

• Pharmaceutical Industry: As an intermediate in the synthesis of active pharmaceutical ingredients (APIs)

• Fuel Additive: Used to improve octane rating in gasoline formulations

Safety and Handling of Toluene

• GHS Classification: Flammable liquid; hazardous to human health and the environment

Hazard Statements (H-Codes):

• H225: Highly flammable liquid and vapor

• H304: May be fatal if swallowed and enters airways

• H315: Causes skin irritation

• H336: May cause drowsiness or dizziness

• H361d: Suspected of damaging the unborn child

• H373: May cause damage to organs through prolonged or repeated exposure

Required Personal Protective Equipment (PPE)

• Chemical-resistant gloves (nitrile or butyl rubber)

• Safety goggles or face shield

• Respiratory protection in areas with high vapor concentration

• Solvent-resistant protective clothing

Storage Conditions

• Store in a cool, dry, and well-ventilated area

• Keep away from heat sources, sparks, and open flames

• Use sealed metal or glass containers resistant to solvents

Emergency Measures

• Inhalation: Move the person to fresh air and seek medical attention

• Skin Contact: Wash thoroughly with soap and water

• Eye Contact: Rinse immediately with plenty of water and get medical assistance

• Ingestion: Do not induce vomiting; seek immediate medical attention