ArBr

ArBr is a common shorthand in organic chemistry for an aryl bromide, a compound in which a bromine atom is bonded directly to an aromatic ring. The Ar designation stands for an aryl group (for example, phenyl), so ArBr covers a wide family of mono- and polybrominated arenes, such as bromobenzene and its substituted derivatives.

Preparation methods typically involve electrophilic bromination of arenes using bromine in the presence of a Lewis acid catalyst (for example FeBr3 or AlBr3). Electron-rich or activated rings brominate more readily, while unactivated rings may require harsher conditions or alternative routes. Other approaches include functional-group transformations that convert other precursors into aryl bromides.

Reactivity and applications: Ar–Br bonds are widely used as leaving groups in transition-metal-catalyzed cross-coupling reactions, including Suzuki–Miyaura, Heck, and Sonogashira couplings. These reactions enable the construction of biaryl, vinyl, and alkynyl products. In general, aryl bromides undergo oxidative addition more readily than aryl chlorides but less readily than aryl iodides, providing a balance between stability and reactivity for synthetic planning.

Properties and use: Many aryl bromides are liquids or solids with varied physical properties; for example, bromobenzene has a boiling point around 156°C. ArBr substrates are common building blocks in pharmaceuticals, agrochemicals, and materials science, where they serve as versatile precursors for complex organic molecules.

Safety: Brominated arenes can be irritants and may pose health hazards; they should be handled in a fume hood with appropriate protective equipment and disposed of as halogenated waste according to guidelines.