Question 5.SSE.14: Which of the following is the correct method for synthesizin......
Which of the following is the correct method for synthesizing methyl-t-butyl ether and why?
(i) \left( CH _3\right)_3 CBr + NaOMe \rightarrow
(ii) CH _3 Br + NaO – t – Bu \rightarrow
[IIT, 1997]
In these two methods,method (ii) is the correct method for the formation of ether because in method (i) alkene is formed in place of ether.
(i) \begin{matrix} \left( CH _3\right)_3 C& -& Br &+& Na& -& O &-& Me \rightarrow & CH _3&-& C &= &CH _2&+& NaBr &+& CH _3 OH \\ &&&&&&&&&&& | \\ &&&&&&&&&&& CH_3 \\ &&&&&&&&&&& \text{Isobutene}\end{matrix}
(ii) \begin{matrix} &&&&&&CH_3 &&&&&& CH_3 \\ &&&&&&| &&&&&& | \\ CH _3 Br& +& Na& -& O& -& C &-& CH _3 &\longrightarrow & H _3 C &- &C& -& O &-& CH _3&+& NaBr \\ &&&&&&| &&&&&& | \\ &&&&&&CH_3 &&&&&& CH_3\end{matrix}
This reaction is known as Williamson’s synthesis and it is based upon SN² reaction mechanism.