Benzene
Description
Benzene (cyclohexa-1,3) is the basis of a group of hydrocarbons referred to as “aromatics”. It is a clear colorless liquid, with a characteristic aromatic smell. Benzene is produced worldwide in substantial quantities, and because it is very easy to transport by ship, it is traded internationally.
Properties
| Parameter | Unit | Quantity |
|---|
| Molecular weight | g/mol | 78.11 |
| Physical state | > 5.5°C | Liquid |
| < 5.5°C | Solid |
| Color | | Clear, colorless |
| Odor | | Aromatic |
| Boiling range/point | °C | 80.1 |
| Melting point | °C | 5.5 |
| Flash point (PMCC) | °C | -11.1 |
| Explosion limits | %, measured as V/V | 1.3 ~ 7.1 |
| Solubility in water | at 25°C, kg/m3 | 0.189/1009 of H2O |
| Vapor pressure | kPa, at 20°C (measured as N/m2) | 99.45 |
| Density | at 20°C, kg/m3 | 879 |
| Auto-flammability | °C | 498 |
| Vapor density | air | 2.7 |
| CAS number | 71-43-2 |
| IUPAC name | Benzene |
Specifications
| Parameter | Unit | Quantity | Test Method |
|---|
| Purity | wt % | 99.85 min. | ASTM D-4492 |
| Non-aromatic | wt % | 0.15 max. | ASTM D-4492 |
| Toluene | wt % | 0.05 max. | ASTM D-4492 |
| Solidification point | °C | 5.35 min. | ASTM D-852 |
| Distillation range | °C, at 760 mmHg, °C | 1.0°C max., including 80.1°C | ASTM D-850 |
| Relative density | at 15.56°C/15.56°C | 0.882 - 0.886 | ASTM D-4052 |
| Appearance | at 18.3 to 25.6°C | clear liquid, free of sedimentation or haze | visual inspection |
| Color | Hazen, Pt/Co scale | 20 max. | ASTM D-1209 |
| Acid wash color | - | 1 max. | ASTM D-848 |
| Acidity | - | no free acid | ASTM D-847 |
| Total sulfur | ppm, wt | 1 max. | ASTM D-4045 |
| Copper corrosion | - | pass 1a or 1b | ASTM D-849 |
| Bromine index | mg/100 mg | 20 max | ASTM D-1492 |
| Thiophene | ppm, wt | 1.2 max | ASTM D-4735 |
| Basic nitrogen | ppm, wt | 0.1 max | UOP-269 |
Note:
- ASTM : American Society for Testing and Materials.
Hazards and safety
Main hazards: may cause cancer.
Toxic: Danger of serious damage to health by prolonged exposure through inhalation, skin contact and if swallowed. Highly flammable.
Eyes: Liquid will cause conjunctival irritation.
Skin: Harmful amounts may be absorbed through skin contact. Repeated or prolonged contact may produce defatting of the skin leading to irritation and dermatitis.
Ingestion: Based on experience of accidental ingestion in humans, effects expected would be: irritation of mouth, throat and digestive tract, vomiting, central nervous system depression, and loss of consciousness. Estimated fatal dose for adults is 10-30 mls. Aspiration during swallowing or vomiting may severely damage the lungs.
Inhalation: Exposure to vapor may have the following effects: euphoria, dizziness, headache, nausea, impaired balance, convulsions and collapse. Exposure to vapor at concentrations of 7500 ppm and above may result in sudden collapse and death from respiratory paralysis.
Applications
Benzene is a very important basic chemical. It is the starting point for many derivatives required in the production of a wide range of goods used in everyday life. For example, benzene and ethylene are used to produce styrene, from which polystyrene is made. It is also used to produce cyclohexane, a precursor to caprolactam, which is used to produce nylon. Well-known commodity chemicals like polystyrene and nylon are subsequently used to manufacture everyday items including clothing, paints, computer casings and packaging.
Storage and handling
Avoid contact with eyes, skin and clothing. Avoid inhaling vapor. Storage and transfer equipment should be adequately earthed and bonded to prevent the accumulation of static charges. The storage area should be well ventilated. Store away from sources of heat or ignition. Do not store in certain rubbers. Suitable storage materials are rust-free carbon steel or most normal metals used for onstruction.