Aniline is an aromatic primary amine compound. Aniline belongs to Nitrogen substituted organic compounds. In this tutorial, you can learn aniline preparing, reactions and characteristics of aniline. Aniline has some different characteristics than other primary amines.
Preparation of aniline from benzene is explained below.
There are two steps to prepare aniline from benzene and they are explained in detail.
Aniline is an activatator and it is also an ortho-para director. We study following reactions of aniline. Electrons' density of benzene ring in aniline is much higher than benzene and that is the reason why aniline shows different reactions than benzene..
Secondary amines or tertiary amines or quaternary ammonium salts can be given from reaction of aniline and alkyl halides. The product depends on the amount of available aniline and alkyl halide.
Secondary amines are given as the major product.
Tertiary amines are given by the reaction of aniline and excess alkyl halide. If there are more alkyl halides, quaternary ammonium salts are given.
Aniline reacts with liquid bromine to give 2,4,6-tribromoaniline which is a white powder. Though aniline reacts with liquid bromine, benzene does not. This reaction proves that aniline has a higher electron density in the benzene ring than the benzene ring in benzene.
Aniline reacts with liquid chlorine to give 2,4,6-trichloroaniline. As with liquid bromine, 2,4,6-trichloroaniline is a white powder.
This reaction is used to prepare phenol or benzene diazonium chloride according to the temperature. Because, Nitrous acid is not a stable acid and readily decomposes, Nitrous acid has to be prepared when it is required. Sodium nitrite and dilute hydrochloric acid (NaNO2 and HCl) are mixed at low temperature to prepare nitrous acid (HNO2).
Nitrous acid is prepared by mixing sodium nitrite and dilute hydrochloric acid. ( NaNO2 / HCl ). Aniline reacts with nitrous acid in two ways.
When reaction occurs below 50C, benzene diazonium chloridee is given as the product.
In room temperature or above 100C, phenol is given as the product of aniline and nitrous acid reaction.
Aniline has weak basic characteristics and HCl is a strong acid. Aniline reacts with HCl acid and forms Aniline hydrochloride (C6H5NH3+Cl-) which has weak acidic characteristics.
Aniline is a primary aromatic amine compound. But some of aniline reactions differ from other primary amine reactions because aniline has a benzene ring. As an example aniline gives benzene diazonium salt with nitrous acid below 50C. But other primary aliphatic amines give primary alcohols with nitrous acid below 50C.
It takes only two steps. First benzene is converted into nitrobenzene. Then nitrobenzene is converted to aniline.
We know, aniline is basic and phenol is acidic. So aniline can react with acids and phenol reacts with bases.
Electrons density of benzene ring in aniline is higher than benzene. Therefore electrophilic substitution reactions are occurred easily than benzene.
Example: Aniline reacts with bromine liquid to give 2,3,4-dibromoaniine. But benzene does not give products with Br2(l). Benzene requires a lewis acid catalyst to give products with Br2(l)
Aniline is a weak base. It reacts with HCl and forms a weak acid (phenylammonium chloride).