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NCERT Class XII Chemistry
Chapter - Alcohols, Phenols and Ethers
Questions with Solutions

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Question : 25
Total: 45
Illustrate with examples the limitations of Williamson synthesis for the preparation of certain types of ethers.
Solution:  
The main limitation of Williamson’s ether synthesis lies in its unemployability for preparation of unsymmetrical ethers where the compound contains secondary or tertiary alkyl groups.
e.g., reaction between tert-butyl bromide and sodium methoxide yieldsan alkene
H3C−
CH3
|
C
|
CH3
−Br
tret−Butylbromide
+NaOCH3––––––––▶
H3C−
CH2
||
C
|
CH3
2−Mthylpropane
+NaBr+CH3OH
This is because the competing elimination reaction predominates over SN2 and alkene is formed.
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