Question

Give the necessary conditions and equations of getting ethanol from:
(a) an alkyl halide
(b) an ethene

Answer 1

(a) The hydrolysis of an alkyl halide by a dilute alkali can yield ethanol. The equation is:

$\underset{\mathrm{Ethyl}\mathrm{bromide}}{{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Br}}+\underset{\mathrm{Aqueous}}{\mathrm{KOH}}\to \underset{\mathrm{Ethanol}}{{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}}+\mathrm{KBr}$

(b) Ethene, upon treatment with concentrated sulphuric acid at 80^oC and 30 atm pressure, gives ethyl hydrogen sulphate, which reacts with boiling water or steam to give ethanol, while sulphuric acid is recovered:

$$\begin{gathered} \underset{\mathrm{Ethene}}{{\mathrm{C}}_2{\mathrm{H}}_4}+\underset{\mathrm{Conc}.}{{\mathrm{H}}_2{\mathrm{SO}}_4}\underset{80°\mathrm{C}}{\overset{80\mathrm{atm}}{\to }}\underset{\mathrm{Ethyl}\mathrm{hydrogen}\mathrm{sulphate}}{{\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{HSO}}_4} \\ {\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{HSO}}_4+\underset{\mathrm{Boiling}}{{\mathrm{H}}_2\mathrm{O}}\stackrel{}{\to }\underset{\mathrm{Etanol}}{{\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}}+{\mathrm{H}}_2{\mathrm{SO}}_4 \end{gathered}$$