Editing Cumene process (section)

==Steps of the process==
Cumene is formed in the gas-phase [[Friedel–Crafts reaction#With alkenes|Friedel–Crafts alkylation]] of benzene by propene. Benzene and propene are compressed together to a pressure of 30 [[Atmospheric pressure|standard atmospheres]] at 250&nbsp;°C in presence of a [[catalyst|catalytic]] [[Lewis acid]]. [[Phosphoric acid]] is often favored over [[aluminium]] [[halide]]s. Cumene is oxidized in air, which removes the tertiary [[benzyl]]ic hydrogen from cumene and hence forms a cumene [[radical (chemistry)|radical]]:
::[[Image:Cumene-radical-formation-2D-skeletal V2.svg|300px]]
The cumene radical then [[chemical bond|bonds]] with an oxygen molecule to give cumene [[peroxide]] radical, which in turn forms [[cumene hydroperoxide]] (C<sub>6</sub>H<sub>5</sub>C(CH<sub>3</sub>)<sub>2</sub>O<sub>2</sub>H) by abstracting a benzylic hydrogen from another cumene molecule. This latter cumene converts into cumene radical and feeds back into subsequent chain formations of cumene hydroperoxides. A pressure of 5 [[Atmosphere (unit)|atm]] is used to ensure that the unstable peroxide is kept in liquid state.
::[[Image:Cumene-peroxide-radical-formation-2D-skeletal.svg|300px]]
::[[Image:Cumene-hydroperoxide-formation-2D-skeletal.svg|450px]]
Cumene hydroperoxide undergoes a [[rearrangement reaction]] in an [[acid]]ic medium (the '''Hock rearrangement''') to give [[phenol]] and [[acetone]]. In the first step, the terminal hydroperoxy oxygen atom is protonated. This is followed by a step in which the phenyl group migrates from the benzyl carbon to the adjacent oxygen and a water molecule is lost, producing a [[resonance (chemistry)|resonance]] stabilized tertiary [[carbocation]]. The concerted mechanism of this step is similar to the mechanisms of the [[Baeyer–Villiger oxidation]]<ref>{{cite book|last=Streitwieser|first=A|author2=Heathcock, C.H.|others=Kosower, E.M.|title=Introduction to Organic Chemistry|publisher=MacMillan|location=New York|year=1992|edition=4th|pages=[https://archive.org/details/introductiontoor00stre_0/page/1018 1018]|chapter=30|isbn=0-02-418170-6|chapter-url=https://archive.org/details/introductiontoor00stre_0/page/1018}}</ref> and [[Criegee rearrangement]] reactions, and also the oxidation step of the [[Hydroboration–oxidation reaction#Hydroboration–oxidation|hydroboration–oxidation]] process.<ref>{{cite book|last=K.P.C.|first=Vollhardt|author2=N.E. Schore|authorlink2=Neil E. Schore|title=Organic Chemistry: Structure and Function|publisher=Freeman|location=New York|year=2003|edition=4th|chapter-url=https://archive.org/details/organicchemistry00voll_0/page/988 |page=988|chapter=22|isbn=0-7167-4374-4}}</ref>
In 2009, an acidified [[bentonite]] clay was proven to be a more economical catalyst than [[sulfuric acid]] as the acid medium.
::[[Image:Cumene-process-phenyl-migration-2D-skeletal V2.svg|450px]]

The resulting [[carbocation]] is then attacked by water, forming a [[hemiacetal]]-like structure. After transfer of a proton from the hydroxy oxygen to the ether oxygen, the ion falls apart into phenol and acetone.

::[[Image:Cumene-process-final-steps-2D-skeletal.svg|600px]]