Preparation of Aromatic Aldehydes & Ketones

PREPARATION OF AROMATIC ALDEHYDES & KETONES

1. By oxidation of alkyl benzene

Aromatic aldehydes are obtained by oxidation of side chain in the aromatic ring.

Illustration 1. How will you prepare benzaldehyde commercially?

Solution: It is prepared form toluene.

2. By Friedel crafts reaction (Refer to hydrocarbons)

Illustration 2. In the following electrophilic substitution reaction.

(i) Identify the compound A.

ii) Write the structure of the electrophite.

Solution:

3. By Gattermann Koch Reaction

In this method aromatic aldehydes are prepared by formylation of aromatic ring with carbon monoxide.

4. From Grignard's reaction

Both aliphatic & aromatic aldehyde can be obtained by this method.

HCN on treatment with Grignard's reagent & subsequently followed by hydrolysis yield an aldehyde.

Similarly