The carbonyl group of aldehydes and ketones can be reduced to a methylene group
by Clemmensen reduction or Wolff-Kishner reduction Aldehydes are easily
oxidised to carboxylic acids by mild oxidising reagents such as Tollens’ reagent and
Fehling’s reagent These oxidation reactions are used to distinguish aldehydes from
ketones Carboxylic acids are prepared by the oxidation of primary alcohols, aldehydes
and alkenes by hydrolysis of nitriles, and by treatment of Grignard reagents with
carbon dioxide