Nitrobenzene is reduced to aniline by Sn and concentrated HCl. Instead of Sn, Zn or Fe also can be used. Aniline salt is given from this reaction. Then aqueous NaOH is added to the aniline salt to get released aniline. This reaction is called nitrobenzene reduction. Benzene is a clear, colourless, highly flammable and volatile, liquid compound. Aniline is a yellowish to brownish oily liquid with a musty fishy odour organic compound.