(ii) Reduction to hydrocarbons: The carbonyl group of aldehydes
and ketones is reduced to CH2 group on treatment with zinc-
amalgam and concentrated hydrochloric acid [Clemmensen
hydrazone
hydrazine
Rationalised 2023-24
239
Aldehydes, Ketones and Carboxylic Acids
reduction] or with hydrazine followed by heating with sodium
or  potassium hydroxide in high boiling solvent such as ethylene
glycol (Wolff-Kishner reduction) 3 Oxidation
Aldehydes differ from ketones in their oxidation reactions Aldehydes
are easily oxidised to carboxylic acids on treatment with common
oxidising agents like nitric acid, potassium permanganate, potassium
dichromate, etc