Question

(a) State how the following conversions can be carried out :
(i) Ethyl chloride to Ethyl alcohol
(ii) Ethyl chloride to Ethene
(iii) Ethene to Ethyl alcohol
(iv) Ethyl alcohol to Ethene

(b) (i) Define Isomerism.
(ii) Give the IUPAC name of the isomer $C_4{H}_{10}$ which has a branched chain.

[5 MARKS]

Answer 1

Part (a) each subpart: 1 Mark
Part (b) each subpart: 0.5 Mark

a) i) Treat ethyl chloride with aqueous potassium hydroxide solution
$\underset{Ethylchloride}{C_2{H}_{5}Cl}+KOH\left(aqueous\right)\stackrel{boil}{\to }\underset{Ethylalcohol}{C_2{H}_{5}OH}+KCl$

ii) Treat ethyl chloride with alcoholic potassium hydroxide solution.
$\underset{Ethylchloride}{C_2{H}_{5}Cl}+KOH(alc.)\to \underset{Ethene}{C_2{H}_4}+KBr+H_{2}O$

iii) Hydration of ethene:
$\underset{Ethene}{C_2{H}_4}+H_{2}O\stackrel{H^{+}}{\to }\underset{Ethanol}{C_2{H}_{5}OH}$

iv) Ethyl alcohol to Ethene (Dehydration of ethyl alcohol):
$\underset{Ethylalcohol}{C_2{H}_{5}OH}\underset{{160}^{\circ }-{170}^{\circ }C}{\overset{conc.H_{2}S{O}_4}{\to }}\underset{Ethene}{C_2{H}_4}+H_{2}O$

(b) i) Isomerism is the existence of two or more compounds having the same molecular formula but different structural formulae.

ii) Isomer of $C_4{H}_{10}$ which has a branched chain: