How do you make phenol from Benzene?
I understand that Nucleophillic substiution isn't happening from let's say chlorobenzene as the pi-electron cloud that is formed inhibits the difference in electronegativity in the C-Cl bond.
I understand that Nucleophillic substiution isn't happening from let's say chlorobenzene as the pi-electron cloud that is formed inhibits the difference in electronegativity in the C-Cl bond.
1 Answer
The vast majority of phenol is made by the cumene process. There are other synthetic pathways discussed in the reference as well.
Explanation:
The production of phenol from benzene is the first step in the manufacture of some very important polymers, including polyamides (nylons), polycarbonates and the phenolic resins.
The vast majority of phenol is made by the cumene process. The process has three stages:
a) production of cumene
In one process, benzene and propene (3:1) are passed over an acid catalyst, usually a zeolite such as ZSM-5 at ca 600 K and under pressure (ca 10 atm) in a fixed bed reactor. The zeolite is more environmentally friendly than traditional acid catalysts such as aluminium chloride. The effluent is much cleaner and lower temperatures and pressures can be used.
b) conversion of cumene to cumene hydroperoxide
Cumene is then oxidized with air to give the hydroperoxide. The reaction is autocatalyzed by cumene hydroperoxide. The reaction takes place at temperatures between 350-390 K and 1-7 atm pressure, the latter to retain the system in the liquid phase.
c) decomposition of cumene hydroperoxide.
Finally, the hydroperoxide is mixed with sulfuric acid at 313-373 K to give, after neutralisation, phenol and propanone. This reaction when carried out with small amounts of sulfuric acid (500 ppm by mass) is termed homogeneous cleavage
