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The resonance can be shown by depicting the charge as being in the para, ortho, and meta positions. (v) Aniline does not undergo Friedel-Crafts reaction: A Friedel-Crafts reaction is carried out in the presence of AlCl 3. It is likely that the p-nitroaniline product arises by the rapid nitration of the minuscule amount of highly reactive unprotonated aniline in the reaction mixture. Let's try an example.
116) The ortho/para product ratio is expected to be the smallest for the bromination of which of these? 0 0 2. Because nitro groups are meta-directing, the product will be m-dinitrobenzene.
In this work, we would like to study the substituent effects of NH 2 and NO 2 groups on benzene using Kohn–Sham density functional theory. Can we extend this analysis to groups which are meta directing? The aldehyde carbonyl group (and carbonyl groups in general) is a metadirecting substituent.We'll look at the resonance structures of the intermediate for an explanation:
Experiment 16 – Electrophilic Aromatic Substitution Page 6 of 8 Figure 11. predict the product or products formed from the reaction of a given monosubstituted benzene derivative with each of the electrophiles discussed in this chapter. nitric acid is a strong acid hence it protonates forming anilinium ion anilinium ion is meta directing because of positive charge on nitrogen ion.hence meta nitro aniline is formed . Aniline in presence of strong acids mainly gives the m-substituted product although aniline is o,p-directing in aq. Substituents already present on a benzene ring also influences the rate of reaction.
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.
115) What is a feature found in all ortho-para directing groups? 1: Thus, the methyl group is an ortho, para directing group. For this reason, aniline on nitration gives a substantial amount of m-nitroaniline. Moreover, in the strongly acidic medium, aniline is protonated to form the anilinium ion which is meta directing. Meta Directive Effects. 7 years ago. A summary of the directing effects of common substituent groups is given in the third column of Table 16.2.
That is why besides the ortho and para derivatives, significant amount of meta derivative is …
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. As is known, these two substituents have completely opposite electronic properties and therefore, opposite effects on the electrophilic substitution reactions of benzene.
c) The group has the ability to delocalize the positive charge of the arenium ion. Meta Addition of an Electrophile to an Activated Aromatic Ring Mechanistically, the pathways for both ortho and para nitration of acetanilide are essentially equivalent, yet when the reaction is …
In an acidic medium, aniline is protonated to give anilinium ion (which is meta-directing).