Question

How is cumene converted into phenol? Give a test to distinguish between phenol and ethanol?

Answer 1

Hint :Here we have two questions. We know that Cumene is an organic compound acquired by Friedel-Crafts alkylation of benzene with propylene. That is, Cumene means isopropyl benzene. On oxidation of cumene and on further action we will get phenol. We can distinguish between phenol and ethanol by reaction with neutral $ FeC{l_3} $ .

Complete step by step solution:
Now conversion of cumene to phenol,
On oxidation of cumene (Isopropyl benzene) in the presence of air, cumene hydroperoxide is found. Upon further action of cumene hydroperoxide with dilute acid, phenols are produced.

Acetone is also made as one of the by-products of the reaction in large quantities. Therefore, phenols prepared by these techniques need purifications.
Now distinguish between phenol and ethanol by reaction with neutral $ FeC{l_3} $ .
Phenol reacts with aqueous neutral $ FeC{l_3} $ to form ferric phenoxide complex, which is violet coloured. But ethanol (alcohol) does not respond to $ FeC{l_3} $ .

Note:
We can prepare phenols from haloarenes or from benzene sulphonic acid or from diazonium salts and by many other methods. We can also distinguish phenol and ethanol by haloform test. Ethanol when treated with an iodine, iodoform is obtained which is yellow needle shaped. But phenol does not show haloform test.
 $ C{H_3}C{H_2}OH\xrightarrow{{{I_2} + O{H^ - }}}CH{I_3} $ .
Phenol is weakly acidic hence turns blue litmus red. It gives a positive dye test, whereas alcohols (ethanol) do not show dye test.