Question

Explain Schiff's reagent test. 

OR 

What is a Schiff's reagent ? How is it used to detect aldehydes?

Answer 1

• Schiff’s reagent is prepared by dissolving pink p-rosaniline hydrochloride (dye Fuchsin) in water and passing SO₂ gas till the pink solution is decolourised.
• Schiff's reagent is an oxidising agent.
• When an aldehyde is added to Schiff's reagent, the colourless solution turns pink or in magenta colour and aldehyde is oxidised to a carboxylic acid.
• This test is not given by ketones, hence, used to distinguish between aldehyde and ketone.