A mixture of `CH_(3)OH` and `C_(2)H_(5)OH` is heated with concentrated `H_(2)SO_(4)` at `140^(@)C`. The product that may be formed is

Options

A. `CH_(3)CH_(2)OCH_(2)CH_(3)`
B. `CH_(3)CH_(2)OCH_(3)`
C. `CH_(3)OCH_(3)`
D. all of these

Answer

D

Explanation

A nonsymmetricai ether is not usually prepared by, heating a mixture of `ROH` and `R'OH` in acid because a mixture of three ethers `ROR,ROR'` and `R'OR'` is obtained. Thus we get all these products.
However it is possible to, prepare `t-`butyl ethyl ether by heating a mixture of `t-`burtanol and ethanol because when one alcohol is `3^(@)`, its onium ion easily loses water to form a carbocation which is solvated by the other `2^(@)` or `1^(@)` alcohol to give mixed ether preferentially.

This is an example of an `S_(N)I` mechanism.
We do not get any `di-t-`butyl ether frorm this reaction because `t-`butanol does not solvate the `3^(@)` carbocation readily because of steric hindrance.