Organic Chemistry — Question 18

(i) By boiling ethyl chloride with aqueous NaOH.

$\underset{\text{ Chloroethane [ethyl chloride]}}{\text{C}_2\text{H}_5\text{-Cl}} + \text{NaOH [aq.]} \xrightarrow{\text{boil}} \underset{\text{ Ethanol [ethyl alcohol]}}{\text{C}_2\text{H}_5\text{OH}} + \text{NaCl}$

(ii) By boiling ethyl chloride with alcoholic KOH.

$\underset{\text{ Chloroethane [ethyl chloride]}}{\text{C}_2\text{H}_5\text{-Cl}} + \underset{\text{ alcoholic KOH}}{\text{KOH [aq.]}} \xrightarrow{\text{boil}} \underset{\text{ Ethene [ethylene]} }{\text{C}_2\text{H}_4} + \text{KCl} +\text{H}_2\text{O}$

(iii) Ethene is absorbed in conc. sulphuric acid at 80 °C under 30 atmos. to give ethyl hydrogen sulphate, which on hydrolysis with steam gives ethanol.

$\underset{\text{ Ethene} }{\text{C}_2\text{H}_4} + \underset{\text{conc.}}{\text{H}_2\text{SO}_4} \underset{30 \text{ atmos.}}{\xrightarrow{80 \degree \text{C}}} \underset{\text{ Ethyl hydrogen sulphate} }{\text{C}_2\text{H}_5\text{-HSO}_4}$

$\underset{\text{ Ethyl hydrogen sulphate }}{\text{C}_2\text{H}_5\text{-HSO}_4} + \underset{\text{steam}}{\text{H}_2\text{O}} \longrightarrow \underset{ \text{ Ethanol [ethyl alcohol]} }{\text{C}_2\text{H}_5\text{-OH}} + \text{H}_2\text{SO}_4$

(iv) By heating ethyl alcohol with concentrated H₂SO₄ at 170°C.

$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170\degree\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\$