Name: Methods of Preparation of Phenol
Uploaded: 2019-07-19
Duration: 3 min 52 s
Description: Phenol is an organic compound, seen even in our households. Let's watch the video and learn the different methods of preparation of phenols.

Question

$2, 4 -$ Dinitrochlorobenzene is converted into picric acid using two paths. Which path, do you think, gives a better result?

Accepted Answer

In path $I$ , $2, 4 -$ dinitrochlorobenzene is nitrated and then, it reacts with sodium hydroxide to give picric acid. The reaction of haloalkane with sodium hydroxide is a nucleophilic substitution reaction, which results in the substitution of chloride with hydroxide ion.

Nitration of an aromatic ring is an electrophilic substitution reaction, hence, the electron-donating group will increase the rate of reaction, while, the electron-withdrawing group will decrease the rate of reaction.

Chlorine group shows $- I$ as well as $+ M$ effect. Hence, chlorine is an ortho para directing and deactivating group. Therefore, in the path $I$ , the nitration before the nucleophilic substitution reaction will decrease the rate of nitration, hence, the yield of picric acid will be low.

In path $II$ , $2, 4 -$ dinitrochlorobenzene is initially reacted with sodium hydroxide and forms $2, 4 -$ dinitrophenol. $OH$ group in phenol is a strong electron-donating group, hence, it behaves as an activating and ortho para directing group. So, its presence will increase the rate of nitration, hence, it would give a better yield of picric acid.

Hence, path $II$ will give better results.

$2, 4 -$ Dinitrochlorobenzene is converted into picric acid using two paths. Which path, do you think, gives a better result?

Important Questions on Aromatic Compounds and Alkyl and Aryl Halides

Learn and Prepare for any exam you want !

2,4 -Dinitrochlorobenzene is converted into picric acid using two paths. Which path, do you think, gives a better result?

Important Questions on Aromatic Compounds and Alkyl and Aryl Halides

Learn and Prepare for any exam you want !

$2, 4 -$ Dinitrochlorobenzene is converted into picric acid using two paths. Which path, do you think, gives a better result?