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