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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
Explain the mechanism of the following reaction:
Write the name of the reagent and the equation for the preparation of the following ether by Williamson’s synthesis:
Ethoxybenzene
Write the name of the reagent and the equation for the preparation of the following ether by Williamson’s synthesis:
2-Methoxy-2-methylpropane
Explain the following with an example.
Williamson ether synthesis
Account for the following :
t-butyl chloride on heating with sodium methoxide gives 2-methylpropene instead of t-butyl methyl ether.
Which of the following cannot be made by using Williamson Synthesis:
Explain why low molecular mass alcohols are soluble in water.
Identify the following named reaction
\[\ce{C2H5Br ->[NaOCH3] C2H5OCH3}\]
Which of the following compounds gives a secondary alcohol upon reaction with methylmagnesium bromide?
Write the equations for the following reaction:
Tert butyl chloride is treated with sodium ethoxide.
The major product [B] in the following reactions is:
\[\begin{array}{cc}\ce{CH3}\phantom{..................................}\\|\phantom{.....................................}\\\ce{CH3 - CH2 - CH - CH2 - OCH2 - CH3 ->[HI][Heat] [A] alcohol ->[H2SO4][\Delta] [B]}\end{array}\]
Which of the following reactions are feasible?
Write the name of the reagent and equation for the preparation of the following ether by Williamson’s synthesis:
2-Methoxy-2-methylpropane
What is metamerism? Give the structure and IUPAC name of metamers of 2-methoxy propane.
What will be the product (X and A)for the following reaction
\[\ce{acetylchloride->[i)CH3MgBr][ii)H3O+]X ->[acidk2crp3]A}\]
Short Answer Question.
Identify the product (s) is / are formed when 1 – methoxy propane is heated with excess HI. Name the mechanism involved in the reaction
Write the names of reagents and equations 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 ether by Williamson’s synthesis:
2-Methoxy-2-methylpropane
Identify the product (s) is/are formed when 1-methoxy propane is heated with excess HI. Name the mechanism involved in the reaction.
