3 From hydrocarbons
Aromatic aldehydes (benzaldehyde and its derivatives) are prepared
from aromatic hydrocarbons by the following methods:
(i) By oxidation of methylbenzene
Strong oxidising agents oxidise toluene and its derivatives to
benzoic acids However, it is possible to stop the oxidation at
the aldehyde stage with suitable reagents that convert the methyl
group to an intermediate that is difficult to oxidise further The
following methods are used for this purpose