Benzene at 200

Summary

In 1825, Michael Faraday discovered one of the most fascinating compounds in chemistry: benzene. While isolating the components of oily residues of illuminating gas, Faraday identified a mysterious liquid, with a peculiar aromatic smell, which would go on to transform the landscape of chemistry. Within the pages of the Philosophical Transactions of the Royal Society of London, Faraday described this seemingly simple yet profoundly unique molecule. What set benzene apart, even in its earliest discovery, was its resistance to easy chemical classification. Its peculiar behaviour, such as its surprising stability despite being highly unsaturated, hinted at a deeper mystery that would not be fully resolved until the mid-19th century with the proposal of its cyclic structure. Benzene’s physical properties only added to its mystique. This colourless liquid emitted a faintly sweet, intoxicating aroma – a hallmark of aromatic compounds. With a boiling point of 80.1°C, it was volatile and highly flammable, making it both a chemical curiosity and a potential industrial tool. Early chemists were captivated by its ability to dissolve fats, oils and other nonpolar substances, which made it a valuable solvent for experimentation and industrial processes. Yet, it was benzene’s chemical properties – its reactivity and stability – that would become the cornerstone of an entire branch of organic chemistry: aromatic compounds. Today, benzene is everywhere, interwoven into the structures of more complex molecules that enhance our daily lives in fields as diverse as health, energy, advanced materials, electronics, food, dyes and biotechnology. This humble molecule opened the doors to a vast universe of aromatic compounds and an endless array of applications that have redefined our world. Stability and tunability Following benzene’s legacy came polycyclic aromatic hydrocarbons (PAHs), a fascinating class of organic molecules composed of fused benzene rings. These structures not only prese...