Phenol, also known as carbolic acid, is an organic compound with the chemical formula C6H5OH. It is a white, crystalline solid. It consists of benzene modified by one hydroxyl (-OH) group. It is produced on a large scale as a precursor to many materials and useful compounds. It is a mildly acidic compound that requires careful handling.
Phenol can be made from the partial oxidation of benzene, by the cumene process, or by the Raschig-Hooker process. It can also be found as a product of coal oxidation. The dominant method starts from cumene (isopropylbenzene):
- C6H5CH(CH3)2 + O2 → C6H5OH + (CH3)2CO
Applications: The major uses of phenol involve its conversion to plastics or related materials. Condensation with acetone gives bisphenol-A, a key building block for polycarbonates. Condensation with formaldehyde gives phenolic resins. Hydrogenation of phenol gives cyclohexanone, an intermediate en route to nylon. Nonionic detergents are produced by alkylation of phenol to give the alkylphenols, which are then subjected to ethoxylation. Phenol is also a versatile precursor to a large collection of drugs, most notably aspirin but also many herbicides and pharmaceuticals.
Niche uses: Phenol is the preferred chemical for embalming bodies for study because of its ability to preserve tissues for extended periods of time. Phenol is also used in the preparation of cosmetics including sunscreens, hair dyes, and skin lightening preparations. In cosmetic surgery, phenol serves as an exfoliant. It is also used in phenolization, a surgical procedure used to treat an ingrown nail, in which it is applied to the nail bed to prevent regrowth of nails. 5% Phenol is sometimes injected near a sensory nerve in order to temporarily (up to a year) stop it from transmitting impulses in some intractable cases of chronic neuropathic pain.