Biphenyl

Biphenyl

Chemical structure of biphenyl Biphenyl is a chemical compound consisting of two benzene rings connected by a single bond. It is also known as diphenyl or phenylbenzene. The molecular formula of biphenyl is C12H10, and its molar mass is 154.21 g/mol. This aromatic hydrocarbon is widely used in various industries due to its unique properties.

Properties

Biphenyl is a colorless solid with a distinct pleasant odor. It has a melting point of 69.2 °C and a boiling point of 255.7 °C. The compound is insoluble in water but soluble in organic solvents such as ethanol and benzene. Biphenyl is nonpolar and exhibits low reactivity, making it relatively stable under normal conditions.

Production

Biphenyl can be synthesized through several methods. One common method is the Friedel-Crafts reaction, where benzene reacts with benzene chloride in the presence of a Lewis acid catalyst. Another method involves the dehydrogenation of 1,2-diphenylethane using a suitable oxidizing agent. Industrial production of biphenyl often involves the distillation of coal tar, which contains various aromatic compounds.

Uses

Biphenyl has numerous applications in different industries. One of its primary uses is as a heat transfer fluid in various heat exchange systems. Its low viscosity and high thermal stability make it an ideal choice for this purpose. Biphenyl is also used as a precursor in the production of polychlorinated biphenyls (PCBs), which were widely used as electrical insulators and coolants before their environmental hazards were discovered.

In addition, biphenyl finds applications in the production of dyes, pharmaceuticals, and fragrances. It is used as a starting material in the synthesis of various organic compounds. Biphenyl derivatives, such as biphenylcarboxylic acid, are utilized in the manufacturing of liquid crystals, which are essential components in electronic displays.

Safety and Environmental Concerns

Biphenyl is considered to be relatively low in toxicity. However, prolonged exposure to high concentrations of biphenyl vapor or dust may cause irritation to the respiratory system and eyes. It is important to handle and store biphenyl properly to prevent any potential health risks.

Due to the environmental persistence and bioaccumulation potential of biphenyl, its use has been restricted in many countries. The production and disposal of biphenyl and its derivatives should be carried out in accordance with local regulations to minimize environmental impact.

See Also

• Polychlorinated biphenyls
• Aromatic hydrocarbon
• Heat transfer fluid