Chemistry Class 12 NCERT Solutions: Chapter 11 Alcohols Phenols and Ethers Part 5 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q: 12. You are given benzene, conc. and . Write the equations for the preparation of phenol using these reagents.


Q_12_Benzene is Fused with H2SO4 and NaOH to Produce Phenol

Q: 13. Show how will you synthesize:

(i) 1-phenylethanol from a suitable alkene

(ii) cyclohexylmethanol using an alkyl halide by an reaction.

(iii) pentan-1-ol using a suitable alkyl halide?


(i) By acid-catalyzed hydration of ethylbenzene (styrene) , 1-phenylethanol can be synthesized.

Q_13_ (I) _Phenylethanol

(ii) When chloromethylcyclohexane is treated with sodium hydroxide, cyclohexylmethanol is obtained.

Q_13_ (II) _Chloromethylcyclohexane is Fused with NaOH to Prod …

(iii) When 1-chloropentane is treated with , pentan-1-ol is produced.

Q: 14. Give two reactions that show the acidic nature of phenol. Compare acidity of phenol with that of ethanol.


The acidic nature of phenol can be represented by the following two reactions:

(i) Phenol reacts with sodium to give sodium phenoxide, liberating .

Q_14_i_Phenol and Sodium Phenoxide

(ii) Phenol reacts with sodium hydroxide to give sodium phenoxide and water as by- products

Q_14_ii_Sodium Phenoxide

The acidity of phenol is more than that of ethanol. This is because after losing a proton, the phenoxide ion undergoes resonance and gets stabilized whereas Ethoxide ion does not.

Q_14_ii_1_The Acidity of Phenol is More Than That of Ethanol

Q: 15. Explain why is ortho nitrophenol more acidic than ortho methoxyphenol?


Q_15_o-Nitrophenol and O-Methoxyphenol

The nitro-group is an electron-withdrawing group. The presence of this group in the ortho position decreases the electron density in the bond. As a result, it is easier to lose a proton. Also, the o-nitrophenoxide ion formed after the loss of protons is stabilized by resonance. Hence, ortho nitrophenol is a stronger acid.

On the other hand, Methoxy group is an electron-releasing group. Thus, it increases the electron density in the bond and hence, the proton cannot be given out easily. For this reason, ortho-nitrophenol is more acidic than ortho-methoxyphenol.

Q: 16. Explain how does the group attached to a carbon of benzene ring activate i towards electrophilic substitution?


The − OH group is an electron-donating group. Thus, it increases the electron density i the benzene ring as shown in the given resonance structure of phenol.

Q_16_The Benzene Ring as Shown in the Given Resonance Struct …

As a result, the benzene ring is activated towards electrophilic substitution.

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