Question

Which reagent can be used to convert ethanol to diethylether?

• A. $A{l}_2{O}_3$ at ${250}^{\circ }C$
• B. conc. $H_{2}S{O}_4$ at ${170}^{\circ }C$
• C. conc. $H_{2}S{O}_4$ at ${140}^{\circ }C$
• D. $A{l}_2{O}_3$ at ${350}^{\circ }C$

Answer 1

The correct option is C conc. $H_{2}S{O}_4$ at ${140}^{\circ }C$

Alkene and ether both are formed on dehydration of an alcohol.Dehydration of alcohols is useful only for the preparation for symmetrical ethers.​
This depends on the reaction conditions.​
If dehydration of alcohol takes place at 443 K, then elimination reaction takes place and alkene is formed.
If dehydration of alcohol takes place at 413 K, then $S_{N}2$ reaction takes place and ether is formed.
Hence, the correct answer is option (c).
$C{H}_{3}C{H}_{2}OH+C{H}_{3}C{H}_{2}OH+H_{2}S{O}_4\stackrel{{140}^{0}C}{\to }C{H}_{3}C{H}_{2}OC{H}_{2}C{H}_3+H_{2}O+H^{+}$
So, the correct option is (c).
The mechanism of dehydration of alcohol involves 3 steps.​
(i) Protonation of alcohol​

(ii) Nucleophilic attack​

(iii) Deprotonation of ether​