Victor Meyer's Test

This three-step test converts an alcohol into a nitroalkane and reads its colour with alkali. Step 1: the alcohol is converted to an alkyl iodide with I2/red phosphorus. Step 2: the alkyl iodide is treated with AgNO2 to give the corresponding nitroalkane. Step 3: the nitroalkane is treated with nitrous acid (from NaNO2/HCl) and the mixture is then made alkaline with KOH. Result: a PRIMARY alcohol (via a 1-nitroalkane) gives a RED colour with KOH; a SECONDARY alcohol (via a secondary nitroalkane, which forms a nitrolic acid with HNO2) gives a BLUE colour; a TERTIARY alcohol (whose …