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प्रश्न
Why does acetylation of –NH2 group of aniline reduce its activating effect?
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उत्तर
Direct nitration of aniline is not possible on account of oxidation of –NH2 group. However, nitration can be carried after protecting the –NH2 group by acetylation to give acetanilide which is then nitrated and finally hydrolysed to give o- and p-nitroanilines.
The acetyl group being electron-withdrawing attracts the lone pair of electrons of the N-atom towards carbonyl group.
As a result, the activating effect –NH2 group is reduced i.e., the lone pair of electrons on nitrogen is less available for donation to benzene ring by resonance. Therefore, activating effect of –NHCOCH3 group is less than that of –NH2 group.
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संबंधित प्रश्न
Illustrate the following reaction giving suitable example in each case: Diazotisation
Write equations of the following reactions:
Acetylation of aniline
Arenium ion involved in the bromination of aniline is:
(i)
(ii)
(iii)
(iv)
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p-toluidine diazonium chloride `→` p-toluic acid
Match the compounds given in Column I with the items given in Column II.
| Column I | Column II | ||
| (i) | Benzene sulphonyl chloride | (a) | Zwitter ion |
| (ii) | Sulphanilic acid | (b) | Hinsberg reagent |
| (iii) | Alkyl diazonium salts | (c) | Dyes |
| (iv) | Aryl diazonium salts | (d) | Conversion to alcohols |
A colourless substance ‘A’ \[\ce{(C6H7N)}\] is sparingly soluble in water and gives a water soluble compound ‘B’ on treating with mineral acid. On reacting with \[\ce{CHCl3}\] and alcoholic potash ‘A’ produces an obnoxious smell due to the formation of compound ‘C’. Reaction of ‘A’ with benzenesulphonyl chloride gives compound ‘D’ which is soluble in alkali. With \[\ce{NaNO2}\] and \[\ce{HCl}\], ‘A’ forms compound ‘E’ which reacts with phenol in alkaline medium to give an orange dye ‘F’. Identify compounds ‘A’ to ‘F’.
Predict the reagent or the product in the following reaction sequence.
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Benzene diazonium chloride is a ______.
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(i) p-methyl aniline
(ii) N, N-dimethylaniline
(iii) N-ethyl aniline
(iv) N-ethyl-N-methyl aniline
The compounds which do not form diazonium salt with ice-colds NaNO2 and HCl are:
Major Product In the above chemical reaction, intermediate "X" and reagent/condition "A" are:
