Testing for Aldehydes and Ketones

Testing for Aldehydes and Ketones

Aldehydes are oxidised by mild oxidising agents to the corresponding carboxylic acid, but ketones are not oxidised.

Tollens' Reagent:

• Tollens' reagent is ammoniacal silver nitrate (AgNO3, NaOH, NH3)
• Heat mixture in a water bath
• When warmed with an aldehyde a silver mirror can be seen
  • the aldehyde is oxidised - 
    • R-CHO + [O] ---> R-COOH
  • the silver (I) ion in silver nitrate is reduced - 
    • Ag+ (aq) + e-  --->  Ag (s)
• Ketones are not oxidised by mild oxidising…