| where do we find the maximum electron density in aniiline resonance hybrid | the NH2 group is ortho and para directing and a powerful activating group |
| bromination | aniline reacts with bromine water at room temp. to give a white precipitate of 2,4,6-tribromoaniline |
| if we have to prepare monosubstituded aniline derivative how can the activating effect of -NH2 group be controlled | by protecting the -NH2 group by acetylation with acetic anhydride |
| nitration of aniline | it yields tarry oxidation products in addition to nitro derivatives in t eh presence of H2SO4 |
| what happens to aniline in strongly acidic medium | it is protonated to form the anilinium ion which is meta directing |
| how can nitration reaction be controlled and p-nitro derivative can be obtained as the major products | by protecting the NH2 group by acetylation reaction with acetic anhydride |
| sulphonation | aniline reacts with concentrated sulphuric acid to form anilium hydrogen sulphate which on heating with sulphuric acid produces p-aminobenzene sulphonic acid |
| common name of p-aminobenzene sulphonic acid | sulphanilic acid |
| aniline does not undergo friedel-craft reaction | due to the formation with aluminium chloride, the lewis acid, which is a catalyst. due to this, nitorgen of aniline acquires positive charge and hence acts as a strong deactivating group for further reaction |
| how is benzenediazonium chloride prepared | by reaction of aniline with nitrous acid and HCl |
| diazotisation | the conversion of primary aromatic amines into diazonium salts. due to its instability the diazonium salt is not generally stored and is used immediately after it's preparation |
| physical properties of benzenediazonium chloride | colourless crystalline solid. readily soluble in water and is stable in cold but reacts with water when warmed.
-decomposes easily in the dry state
-benzene diazonium fluoroborate is water-insoluble and stable at room temp. |
| reaction involving displacement of nitrogen | diazonium group being a very good leaving group is substituted by Cl,Br, I, CN, and O. |
| replacement by halide or cyanide ion/ sandmeyer's reaction | these nucleophiles can easily be introduced in the benzene ring in the presence of Cu ion |
| gatterman reaction | chlorine or bromine can also be introduced in the benzene ring by treating the diazonium salt solution with corresponding halogen acid in the presence of cu powder |
| where is the yeild better in the reaction involving displacement of nitrogen | sandmeyer reaction |
| reactions involving retention of diazo group coupling reaction | benzene diazonium chloride reacts with phenol in which the phenol molecule at it's para position is coupled with the diazonium salt to form p-hydroxyazobenzene. |
| importance of diazonium salts in synthesis of aromatic compounds | aryl florides and iodides cannot be formed by direct halogenation.
the cyano group cannot be introduced by nucleophilic substitution of chlorine in chlorobenzene but cyanobenzene can easily be obtained from diazonium salts |
