Ammonolysis of alkyl halides followed by the treatment with NaOH  can be used to prepare primary,secondary and tertiary amines.The purpose of NaOH in the reaction is:

Free amine obtained from ammonium salt with NaOH, & acidic impurities are removed by NaOHR−X+NH3→RNH3+X−RNH3X−+NaOH→R−NH2+NaX+H2OSimilarly 2°, 3° amines can also be prepared