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प्रश्न
Illustrate with examples the limitations of Williamson synthesis for the preparation of certain types of ethers.
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उत्तर
The main limitation of Williamson’s ether synthesis is that it cannot be used to prepare unsymmetrical ethers where the compound has tertiary or secondary alkyl groups. For example, a reaction between tert-butyl bromide and sodium methoxide yields an alkene.
\[\begin{array}{cc}
\ce{CH3}\phantom{........................................}\ce{CH2}\phantom{..............}\\
|\phantom{...............................................}||\phantom{.................}\\
\ce{CH3 - C - Br + NaOCH3 -> CH3 - C + NaBr + CH3OH}\\
|\phantom{...............................................}|\phantom{..................}\\
\ce{\underset{tert-Butylbromide}{CH3}\phantom{............................}\ce{\underset{2-Methylpropene}{CH3}}}\phantom{..............}\
\end{array}\]
This is due to the formation of an alkene and the dominance of the competing elimination reaction over SN2.
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संबंधित प्रश्न
Write the name of the reagent and the equation for the preparation of the following ether by Williamson’s synthesis:
1-Propoxypropane
Write the name of the reagent and equation for the preparation of the following ethers by Williamson’s synthesis:
1-Methoxyethane
How is 1-propoxypropane synthesised from propan-1-ol? Write mechanism of this reaction.
Preparation of ethers by acid dehydration of secondary or tertiary alcohols is not a suitable method. Give reason.
Williamson's synthesis of preparing dimethyl ether is a/an ____________.
Explain why low molecular mass alcohols are soluble in water.
Identify the following named reaction
\[\ce{C2H5Br ->[NaOCH3] C2H5OCH3}\]
Name the suitable alcohol and reagent, from which 2-Chloro-2-methyl propane can be prepared.
Which of the following reactions are feasible?
Write the mechanism of the following reaction:
\[\ce{2CH3CH2OH ->[H^+][413 K] CH3-CH2-O-CH2-CH3 + H2O}\]
Write the name of reagent and equation for the preparation of the following ethers by Williamson’s synthesis:
2-Methoxy-2-methylpropane
Write the name of reagents and equations for the preparation of the following ethers by Williamson’s synthesis:
2-Methoxy-2-methylpropane
Write the name of the reagent and equation for the preparation of the following ether by Williamson’s synthesis:
2-Methoxy-2-methylpropane
Write the name of reagent and equation for the preparation of the following ethers by Williamson’s synthesis:
2-Methoxy-2-methylpropane
Predict the major product, when 2-methyl but -2-ene is converted into an alcohol in the following method.
Acid catalysed hydration
Write the name of reagent and equation for the preparation of the following ethers by Williamson’s synthesis:
2-Methoxy-2-methylpropane
Write the name of reagent and equation for the preparation of the following ethers by Williamson’s synthesis:
2-Methoxy-2-methylpropane
Write the name of reagent and equation for the preparation of the following ether by Williamson’s synthesis:
2-Methoxy-2-methylpropane
