C6H5Br

Bromobenzene, with the chemical formula C6H5Br, is an aryl bromide derived from benzene by substituting one hydrogen with a bromine atom. It is commonly referred to as bromobenzene or phenyl bromide. The molecule has a molecular weight of about 157.0 g/mol and consists of a planar benzene ring bearing a single bromine substituent.

Physically, bromobenzene is typically a colorless to pale yellow liquid at room temperature. It has a boiling point near 156 °C and a melting point around −30 °C. It is immiscible with water and is soluble in many organic solvents such as ether, acetone, and chlorinated solvents. It is a flammable liquid and is compatible with standard laboratory glassware and ventilation practices but requires careful handling.

Production and handling in industry commonly involve the bromination of benzene using bromine in the presence of a Lewis acid catalyst, such as iron(III) bromide. The reaction provides bromobenzene and hydrobromic acid as byproducts. Alternative routes include bromination of other benzene derivatives or through transformations of other phenyl precursors.

In organic synthesis, bromobenzene is valued as an aryl bromide substrate, particularly in palladium- or nickel-catalyzed cross-coupling reactions (for example, Suzuki-Miyaura, Heck, and related couplings). Aryl bromides are generally more reactive than the corresponding chlorides in these processes, making bromobenzene a versatile building block for preparing biaryl and substituted arenes.

Safety and environmental considerations are important: bromobenzene is toxic and an irritant to skin, eyes, and the respiratory system, and it poses flammability and environmental risks. It should be handled in a well-ventilated hood with appropriate protective equipment and disposed of as hazardous chemical waste according to local regulations.