Chemistry Class 12 NCERT Solutions: Chapter 11 Alcohols Phenols and Ethers Part 8

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Q: 22. Give reason for the higher boiling point of ethanol in comparison to methoxymethane.

Answer:

Ethanol undergoes intermolecular H-bonding due to the presence of −OH group, resulting in the association of molecules. Extra energy is required to break these hydrogen bonds. On the other hand, methoxymethane does not undergo H-bonding. Hence, the boiling point of ethanol is higher than that of methoxymethane.

Q 22 The Boiling Point of Ethanol is Higher than that of Methoxymethane

Q 22 Boiling Point of Ethanol Higher Than Methoxymethane

Q 22 The Boiling Point of Ethanol is Higher than that of Methoxymethane

Q: 23. Give IUPAC names of the following ethers:

(i)

(ii)

(iii)

(iv)

(v)

Q 23 v IUPAC names

Q 23 v IUPAC Names

Q 23 v IUPAC names

(vi)

Q 23 vi IUPAC names

Q 23 Vi IUPAC Names

Q 23 vi IUPAC names

Answer:

(i) 1-Ethoxy-2-methylpropane

(ii) 2-Chloro-1-methoxyethane

(iii) 4-Nitroanisole

(iv) 1-Methoxypropane

(v) 4-Ethoxy-1, 1-dimethylcyclohexane

(vi) Ethoxybenzene

Q: 24. Write the names of reagents and equations for the preparation of the following ethers b Williamson’s synthesis:

(i) 1-Propoxypropane

(ii) Ethoxybenzene

(iii) 2-Methoxy-2-methylpropane

(iv) 1-Methoxyethane

Answer:

(i)

(ii)

Q 24 ii Ethoxybenzene

Q 24 Ii Ethoxybenzene

Q 24 ii Ethoxybenzene

(iii)

Q 24 iii 2-Methoxy-2-methylpropane

Q 24 Iii 2-Methoxy-2-Methylpropane

Q 24 iii 2-Methoxy-2-methylpropane

(iv)

Q: 25. Illustrate with examples the limitations of Williamson synthesis for the preparation of certain types of ethers.

Answer:

The reaction of Williamson synthesis involves attack of an alkoxide ion on a primary alkyl halide.

Q 25 1 The Limitations of Williamson Synthesis

Q 25 1 the Limitations of Williamson Synthesis

Q 25 1 The Limitations of Williamson Synthesis

But if secondary or tertiary alkyl halides are taken in place of primary alkyl halides, the elimination would compete over substitution. As a result, alkenes would be produced This is because alkoxides are nucleophiles as well as strong bases. Hence, they reac with alkyl halides, which results in an elimination reaction.

Q 25 2 The Limitations of Williamson Synthesis

Q 25 2 the Limitations of Williamson Synthesis

Q 25 2 The Limitations of Williamson Synthesis