Phenolics or Polyphenols are the structural ‘backbone’ for most of the antioxidants found in plants. Plants construct complex phenolic compounds that serve a variety of functions as defense mechanisms and through interactions with other organisms. They may function to protect the plant from insects, diseases, and environmental stress. Phenolics also determine certain desirable plant properties such as flavor and palatability. Some phenols are germicidal and are used in formulating disinfectants. Others possess estrogenic or endocrine disrupting activity.
The phenol-formaldehyde resins, developed commercially between 1905 and 1910, were the first truly synthetic polymers and have found wide usage. They are characterized by low cost, dimensional stability, high strength, and resistance to aging. Various thermosetting resins, obtained by the reaction of phenols with simple aldehyde additives, are used to make molded products, coatings and adhesives.
Items can be cast from syrupy intermediates or molded from solid resins. Laminated products can be produced by impregnating fiber, cloth, wood, and other materials with the resin. An important type of phenolic resin product is rigid foam. Cured phenolic plastics are rigid, hard, and resistant to chemicals (except strong alkali) and to heat. Phenolic resins can be used for making precisely molded articles, such as machine parts. They are useful for manufacturing strong and durable laminated boards, or for impregnating fabrics, wood, and paper. Phenolic resins are also widely used as adhesives, as the binder for grinding wheels, as thermal insulation panels, as ion-exchange resins, and in paints and varnishes.
Natural phenol is a colorless to pink solid or thick liquid with a characteristic sweet tar like odor. It is highly soluble in water, alcohol, chloroform, ether, glycerol, carbon disulphide, petrolatum, volatile and fixed oils, and aqueous alkali hydroxides. It is almost insoluble in petroleum ether. It has a boiling point of 181.8(°C), a melting point of 40.9 (°C), and a flash point of 78.9(°C).
Phenol has proven useful as a general disinfectant, as a reagent in chemical analysis and for the manufacture of artificial resins, medical and industrial organic compounds and dyes. It is also used in the manufacture of fertilizers, explosives, paints and paint removers, drugs, pharmaceuticals, textiles and coke. It is produced in large volume, mostly as an intermediate in the production of other chemicals.
The largest single use of phenol is as an intermediate in the production of phenolic resins, which are low-cost, versatile, thermoset resins used in the plywood adhesive, construction, automotive, and appliance industries. It is also used as an intermediate in the production of caprolactam, which is used to make nylon and other synthetic fibres, and bisphenol A, which is used to make epoxy and other resins.
Phenol is found naturally in animal wastes and decomposing organic material. Phenol is a common component of oil refinery wastes. It is also produced in the conversion of coal into gaseous or liquid fuels and in the production of metallurgical coke from coal. It may enter the environment from oil refinery discharges, coal conversion plants, municipal waste treatment plant discharges, or spills.
Consumer products which may contain Phenol include agricultural chemicals, disinfectants, general antibacterials and antiseptics, household hard surface cleaners (liquid), lubricating oils, automotive chemicals, paint and varnish removers, pharmaceutical preparations, synthetic resin and rubber adhesives, wood office work surfaces (modular systems).