How are ketones made?
1 Answer
There are various ways of synthesising them depending on the specific ketone......
Explanation:
For example, acetone is commonly produced by the oxidation of cumene in the Hock process: propylene and benzene are reacted to form cumene (isopropyl benzene) via a Friedel-Crafts alkylation using phosphoric acid catalyst.
Oxidation of cumene in air creates cumyl radicals by the removal of the tertiary benzylic hydrogen atom, and these react with oxygen from the air to form cumene peroxide radicals, which then form cumene hydroperoxide by removing benzylic hydrogens from other cumene molecules.
Finally acid hydrolysis of the cumene hydroperoxide causes the migration of the phenyl group from the benzyl carbon to the adjacent oxygen with loss of water, and formation of a stable (due to resonance) tertiary carbocation. This is then attacked by water, causing a proton to be transferred from the hydroxy oxygen to the ether oxygen, which leads to the ion breaking into phenol and acetone.
In the laboratory, it is possible to form acetone in a rather simpler process, oxidation of IPA. Isopropyl alcohol is mixed with potassium permanganate and an acid catalyst (conc sulphuric) and warmed, causing oxidation of the alcohol and formation of the carbonyl group. Distillation of the mixture is used to separate off the acetone.
