benzeno

Benzeno is the simplest aromatic hydrocarbon, with the chemical formula C6H6. It is a colorless, volatile liquid at room temperature with a characteristic sweet odor and is highly flammable. It is practically insoluble in water and soluble in many organic solvents. Typical physical properties include a boiling point of 80.1 °C and a melting point of about −5.5 °C.

The molecule features a planar hexagonal ring of six carbon atoms, each bonded to one hydrogen atom. The carbon atoms are sp2-hybridized and the ring contains a delocalized π electron system, which gives benzene its characteristic stability and unusual reactivity as an aromatic compound. The concept of aromaticity and the Kekulé structure contributed to understanding its bonding and reactions.

Historically, benzene was first isolated from coal tar in the 19th century, and its ring structure was proposed by August Kekulé in 1865. In industry, benzene is primarily produced from catalytic reforming of naphtha or other hydrocarbon streams and is also derived from coal tar. It serves as a major feedstock for the production of a wide range of derivatives, including styrene, cumene, aniline, and phenol, which are used in plastics, polymers, dyes, explosives, and nylon precursors.

Chemically, benzene undergoes electrophilic aromatic substitution reactions, such as nitration, sulfonation, halogenation, and Friedel–Crafts alkylation or acylation, with the reactions governed by the ring’s aromatic stability.

Safety and environment: benzene is a known human carcinogen, associated with leukemia and other blood disorders. Long-term exposure is dangerous, and handling requires appropriate controls, ventilation, and containment. Environmental releases require careful management due to its volatility and potential health risks.