In an acidic medium, aniline is protonated to give anilinium ion (which is meta-directing). Sulphonation Sulphuric acid reacts vigorously with aniline to form anilinium hydrogen sulphate which on heating produces sulphanilic acid which in turn also has a resonating structure with zwitter ion as shown in the above figure.
2: Thus, the nitro group is a meta directing group. Hence nitration of aniline give meta nitroaniline as the major product along with para nitroaniline.
1: Thus, the methyl group is an ortho, para directing group. Amines. That is why, besides ortho (2%) and para (51%) derivatives, significant amount (47%) of meta … For this reason, aniline on nitration gives a substantial amount of m-nitroaniline. In strongly acidic medium, aniline is protonated to form anilinium ion which is meta directing. Your question has some confusion in the concepts. (v) Aniline does not undergo Friedel-Crafts reaction: A Friedel-Crafts reaction is carried out in the presence of AlCl 3. Ortho, para directing groups are electron-donating groups; meta directing groups are electron-withdrawing groups. In order to obtain p-nitroaniline as the major product, the -NH₂ group should be protected. Nitration is carried out in an acidic medium ( a mixture of concentrated HNO3 and concentrated H2SO4). If the opposite is observed, the substituent is called a meta directing group. For this reason, aniline on nitration gives a substantial amount of m-nitroaniline. eg.
In acidic (strong) medium aniline is present as anilinium ion.
By protecting the –NH 2 group by acetylation reaction with acetic anhydride, nitration reaction is … Nitration is usually carried out with a mixture of concentrated HNO 3 and concentrated H 2 SO 4. Aniline reacts with strong acids to form anilinium (or phenylammonium) ion (C 6 H 5-NH 3 +). In an acidic medium, aniline is protonated to give anilinium ion (which is meta-directing).
1: Thus, the methyl group is an ortho, para directing group. This protonated amine will then be considered a meta-directing group. In acidic (strong) medium aniline is present as anilinium ion. That is why besides the ortho and para derivatives, significant amount of meta derivative is … If aniline is subjected to direct nitration it yields tarry oxidation products in addition to nitro derivatives. HNO3 and H2SO4. This is why apart from ortho and para derivative, a significant amount of meta derivative is also formed. The anilinium ion carrying a positive charge on nitrogen will pull the electrons towards itself making it meta directing. Class 12th NCERT - Chemistry Part-II 13. Once protonated, the anilinium ion is formed which is a strong deactivator and a meta director. H2SO4, aniline forms aniline hydrogen sulphate in which the anilinium ion, C6H5NH3+ is meta directing because the positive charge on the nitrogen attracts electrons from the benzene ring. eg. It is because the aniline molecule gets protonated in acidic medium to become anilinium ion which is meta directing. The nitration of aniline is carried out using conc. It is a deactivator that will draw electron density away from the ring (because nitrogen, a … Therefore, in presence of acids, the reaction mixture consists of aniline and anilinium ion. This nitrogen basicity makes the direct nitration of aniline impossible. Hope this information will clear your doubts regarding the topic. In the presence of these acids, most of aniline gets protonated to form anilinium ion. Aniline(C6H5NH2) is basic in nature because of lone pair of electron present on Nitrogen and Nitration is carried out in the presence of HNO3(Nitric acid) + H2SO4(Sulphuric acid) : this mixture is also called Nitrating mixture. So, nitration of aniline is carried out by first protecting amino group by acetylation. The anilinium ion has no lone pair of electron to donate to the benzene ring; consequently its electron withdrawing nature makes it meta directing.
One solution to the problem is to use an acetyl group (CH3CO) to “protect” the nitrogen atom during the nitration by …
Aniline in presence of strong acids mainly gives the m-substituted product although aniline is o,p-directing in aq. Hence, nitration of aniline gives meta derivative along with ortho and para.