-> C6H5OH + CO2 + H2O The reaction is proposed to proceed via formation of benzyoylsalicylate. Older methods Early methods relied on extraction of phenol from coal derivatives or the hydrolysis of benzene derivatives. Hydrolysis of benzenesulfonic acid An early commercial route, developed by Bayer and Monsanto in the early 1900s, begins with the reaction of a strong base with benzenesulfonic acid. The conversion is represented by this idealized equation: C6H5SO3H + 2 NaOH -> C6H5OH + Na2SO3 + H2O Hydrolysis of chlorobenzene Chlorobenzene can be hydrolyzed to phenol using base (Dow process) or steam (Raschig–Hooker process): C6H5Cl + NaOH -> C6H5OH + NaCl C6H5Cl + H2O -> C6H5OH + HCl These methods suffer from the cost of the chlorobenzene and the need to dispose of the chloride by product. Coal pyrolysis Phenol is also a recoverable byproduct of coal pyrolysis. In the Lummus Process, the oxidation of toluene to benzoic acid is conducted separately. Miscellaneous methods Phenyldiazonium salts hydrolyze to phenol. The method is of no commercial interest since the precursor is expensive. C6H5NH2 + HCl + NaNO2 -> C6H5OH + N2 + H2O + NaCl Salicylic acid decarboxylates to phenol. Uses The major uses of phenol, consuming two thirds of its production, involve its conversion to precursors for plastics. Condensation with acetone gives bisphenol-A, a key precursor to polycarbonates and epoxide resins. Condensation of phenol, alkylphenols, or diphenols with formaldehyde gives phenolic resins, a famous example of which is Bakelite. Partial hydrogenation of phenol gives cyclohexanone, a precursor to nylon. Nonionic detergents are produced by alkylation of phenol to give the alkylphenols, e.g., nonylphenol, 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 pharmaceutical drugs. Phenol is a component in liquid–liquid phenol–chloroform extraction technique used in molecular biology for obtaining nucleic acids from tissues or cell culture samples. Depending on the pH of the solution either DNA or RNA can be extracted. Medical Phenol is widely used as an antiseptic. Its use was pioneered by Joseph Lister (see section). From the early 1900s to the 1970s it was used in the production of carbolic soap. Concentrated phenol liquids are commonly used for permanent treatment of ingrown toe and finger nails, a procedure known as a chemical matrixectomy. The procedure was first described by Otto Boll in 1945. Since that time it