Question

Give a chemical test to distinguish between the following pair of compounds

1: n-propyl alcohol and isopropyl alcohol

2: methanol and ethanol

3: cyclohexanol and phenol

4: propan-2-ol and 2 methylpropan-2-ol

5: phenol and anisole

6: ethanol and diethyl Ether

Answer 1

1)n-propyl alcohol and isopropyl alcohol can be distinguished by Lucas Test.

ZnCl2 + Conc HCl is called as the Lucas reagent

Lucas test is used to differentiate between primary, secondary and tertiary alcohols. When the substance is passed through ZnCl2 and concentrated HCl, primary alcohols produces no effect ,secondary alcohols produces a cloudy appearance after 5minutes whereas tertiary alcohols produces a cloudy appearance immediately .
So n-propyl alcohol produces no change whereas isopropyl alcohol produces cloudy appearance after 5 minutes

2)Methanol and ethanol can be differentiated by using iodoform test. Ethanol produces a Yellow precipitate of CHI3 on reaction with NaOH and Iodine solution whereas methanol,which do not have a free methyl group doesn't.

3)Cyclohexanol and phenol can be differentiated by using Br2 test. Phenol produces a white precipitate of tribromophenol,whereas cyclohexanol doesn't.

4)Propan-2-ol and 2methyl propan -2-ol can be differentiated using Lucas test as explained before.

5)Phenol and Anisole can be classified by neutral FeCl3 test. Phenol will turn Violet by producing a complex and Anisole doesn't show any colour.

6)Ethanol and diethyl ether can be classified by iodoform test as mentioned above