Arenes are the benzene and its derivatives that refer to hydrocarbons own one or more benzene rings. The origin name is formed in the early organic development, because this class of compounds is almost always found in volatile, scented substances, such as: benzoic acid from benzoin gum, benzaldehyde obtained from bitter almond oil. But many of aromatic compounds are not fragrant, so today's arenes are compounds containing benzene ring. The most simple and most important arenes are benzene and its homologues toluene, xylene, ethylbenzene and so on.
Organic chemistry: Arenes are reactants in many organic reactions. In a coupling reaction, the metal catalyzes the coupling between two types of free radical segments. Common coupling reactions result in the formation of new carbon-carbon bonds such as alkylaromatics, vinylaromatics, carbon-carbon double bonds, carbon-nitrogen bonds (anilines) or new carbon-oxygen bonds (aryloxy compounds).
Fig.1. Suzuki coupling.
Medical chemistry: Salicylic acid is one of the most famous arenes. In ancient times, salicylic acid has been not only used to relieve pain and fever, but also have anti-inflammatory effect. In modern medicine, methyl salicylate is also used to relieve joint and muscle pain; salicylic acid choline is widely used to treat oral ulcers. Salicylic acid is also a key exfoliating ingredient in many skin care products and is used in the treatment of acne, seborrheic dermatitis, psoriasis, corns and keratosis. Topical salicylic acid has antibacterial properties against the microbes, and its corrosion resistance is close to that of phenol.
Industry: The biggest use of benzene is to prepare the styrene, and polystyrene can be obtained by the polymerization of styrene. Polystyrene has excellent electrical properties, with well heat resistance and low price, and has become one of the most commonly used general-purpose plastics today. It is commonly used as shockproof packaging materials. Followed by hydrogenation of benzene into cyclohexane, cyclohexane is the raw materials to produce nylon. The use of nylon includes making fibers and engineering plastics, the fibers can be woven into a variety of fabrics and can also be made into the cords of aircraft and automobile tire. Industrial xylenes are a mixture of three xylene isomers (ortho, meta and para) and ethylbenzene. Among them, para-xylene can be made into terephthalic acid at high temperature, which is the main raw material for synthesizing polyester resin (polyester). Anthracene and naphthalene are polycyclic aromatic hydrocarbons, which are important raw materials for the production of synthetic dyes and pharmaceuticals.