Preparation of aldehydes and ketones by oxidation of
alcohols
Primary or secondary alcohols can be oxidized to aldehydes or ketones. Aldehydes
are easily further oxidized to the corresponding carboxylic acid and oxidation of a
primary alcoholusually continues through the aldehyde to the acid. The oxidation of
asecondary alcoholusually yields a ketone. Ketones are more resistant to further
oxidation because C–C bonds would have to be broken and can only be further oxi-
dized using very strong oxidising conditions. Tertiary alcoholsare resistant to any
oxidation, again because C–C bonds would have to be broken. These changes can be
summarized as follows:
CARBONYL COMPOUNDS 335Oxidation of alcohols
Write the names and formulae of the products of the oxidation of the following compounds:
(i)butan-2-ol (ii)propan-1-ol (iii)octan-2-ol.Exercise 18G
Ethanal is formed when ethanol is oxidized in the liver. A buildup of ethanal in
the bloodstream causes a hangover.
Ketones can have distinctive sweet smells. Spearmint-flavoured chewing gum
gets its flavour from the ketone carvone:
Aldehydes and ketones 2
(i) Why is there no such compound as ethanone?
(ii)Write down the structural formula of the aldehydes that are isomeric with
CH 3 CH 2 CH 2 COCH 3. What are their names?
(iii)Write down the names and structures of two aldehydes and one ketone with the molecular
formula C 4 H 8 O.Exercise 18F