Production
Because of phenol's commercial importance, many methods have been developed for its production. The dominant current route, accounting for 95% of production (2003), involves the partial oxidation of cumene (isopropylbenzene) via the Hock rearrangement:
- C6H5CH(CH3)2 + O2 → C6H5OH + (CH3)2CO
Compared to most other processes, the cumene-hydroperoxide process uses relatively mild synthesis conditions, and relatively inexpensive raw materials. However, to operate economically, there must be demand for both phenol, and the acetone by-product.
An early commercial route, developed by Bayer and Monsanto in the early 1900s, begins with the reaction of a strong base with benzenesulfonate:
- C6H5SO3H + 2 NaOH → C6H5OH + Na2SO3 + H2O
Other methods under consideration involve:
- hydrolysis of chlorobenzene, using base or steam (Raschig-Hooker process):
- C6H5Cl + H2O → C6H5OH + HCl
- direct oxidation of benzene with nitrous oxide, a potentially "green" process:
- C6H6 + N2O → C6H5OH + N2
- oxidation of toluene, as developed by Dow Chemical:
- C6H5CH3 + 2 O2 → C6H5OH + CO2 + H2O
In the Lummus Process, the oxidation of toluene to benzoic acid is conducted separately.
Phenol is also a recoverable byproduct of coal pyrolysis.
Read more about this topic: Phenol
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