Name: Isomerism in Alcohols
Uploaded: 2019-07-19
Duration: 5 min 5 s
Description: Chemical compounds that have the same chemical formulae but differ in property and arrangement of atoms in the molecule are called an isomer. Dive into this...

Question

How ethyl alcohol can be converted to methyl alcohol and vice versa? Write any two reactions by which ethyl alcohol is distinguished from methyl alcohol.

Accepted Answer

Conversion of ethyl alcohol to methyl alcohol:

Ethyl alcohol on oxidation produces Ethanoic acid which on decarboxylation results in the products Methane and Carbon dioxide. The produced Methane on chlorination gives Methyl chloride which further reacts with aqueous $KOH$ gives Methanol.

$\underset{Ethyl alcohol}{{CH}_{3} {CH}_{2} OH} \overset{K_{2} {Cr}_{2} O_{7} / conc . H_{2} {SO}_{4}}{\to} \underset{Ethanoic acid}{{CH}_{3} COOH} \to_{Sodalime, Heat}^{Na - Salt} \underset{Methane}{{CH}_{4}} \to_{hv}^{{Cl}_{2}} \underset{Methyl chloride}{{CH}_{3} Cl} \overset{aq . KOH}{\to} \underset{Methyl alcohol}{{CH}_{3} OH}$

Conversion of methyl alcohol to ethyl alcohol:

Step 1: When methyl alcohol reacts with hydrogen chloride, alcohol group substitutes with chloro group and results in the formation of chloromethane.

Step 2: When chloromethane is reacted with aqueous alcoholic solution of $KCN$ , it results in the formation of ethanenitrile.

$\underset{Methyl alcohol}{{CH}_{3} OH} + HCl \underset{- H_{2} O}{\to} \underset{Chloromethane}{{CH}_{3} Cl} + KCN \underset{- KCl}{\to} \underset{Ethanenitrile}{{CH}_{3} CN}$

Step 3: On hydrolysis of ethanenitrile in hot acidic or alkaline medium, it leads to the formation of ethanoic acid.

Step 4: On reduction of ethanoic acid in the presence of strong reducing agent, it leads to the formation of ethyl alcohol or ethanol.

$\underset{Ethanenitrile}{{CH}_{3} CN} \overset{H^{+}, H_{2} O}{\to} \underset{Ethanoic acid}{{CH}_{3} COOH} \underset{}{\overset{{LiALH}_{4} / Ether, H^{+}, H_{2} O}{\to} \underset{Ethyl alcohol}{{CH}_{3} {CH}_{2} OH}}$

Ethyl alcohol can be distinguished from methyl alcohol by performing iodoform test. A few drops of alcohol are warmed with iodine, and sodium or hydroxide, a yellow precipitate of iodoform with characteristic smell is obtained. Methyl alcohol does not respond to iodoform test.

How ethyl alcohol can be converted to methyl alcohol and vice versa? Write any two reactions by which ethyl alcohol is distinguished from methyl alcohol.

Important Questions on Alcohols

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