Question

Which reagent can be used to convert ethanol to diethyl ether?

• A. $A{l}_2{O}_3$ at ${350}^{0}C$
• B. conc. $H_{2}S{O}_4$ at ${130}^0-{140}^{0}C$
• C. $A{l}_2{O}_3$ at ${250}^{0}C$
• D. conc. $H_{2}S{O}_4$ at ${170}^{0}C$

Answer 1

Answer: (B)

In this case, the ethanol is treated by concentrated sulphuric acid $\left(H_{2}S{O}_4\right)$ to form diethyl ether. The acid in an aqueous medium produces hydronium $H_3{O}^{+}$ ion.

$H^{+}$ protonate the oxygen atom of ethanol and the ethanol molecule gets a positively charged oxygen. After that, the oxygen atom of unprotonated ethanol abstracts a $H_{2}O$ molecule from ethanol and produces diethyl ether.

$C{H}_{3}C{H}_{2}OH+H_{2}S{O}_4\stackrel{{140}^{o}C}{\to }C{H}_{3}C{H}_{2}O{H}_2^{+}+H_{2}O$

$C{H}_{3}C{H}_{2}O{H}_2^{+}+C{H}_{3}C{H}_{2}OH\to C{H}_{3}C{H}_{2}OC{H}_{2}C{H}_3+H_{2}O+H^{+}$

So, the correct option is C