Question

Ethane cannot be obtained by which of the following methods?
A) Heating methyl iodide with Sodium metal in ether
B) Hydrogenation of ethene
C) Sodium acetate on Kolbe’s electrolysis
D) Hydrolysis of aluminium carbide

Answer 1

Ethane is a 2-carbon saturated compound with chemical formula of ${C_2}{H_6}$. Every carbon is attached to three hydrogen atoms and the Carbon-Carbon has a single bond between them. It is one of the most commercially used, the one of the simplest hydrocarbons and is present in gaseous state.
Complete step by step answer:
To solve this question, we’ll predict the products of each of the reactions given in the options. The reaction which doesn’t give ethane as the product is our answer.
A) The first reaction given to us is Heating methyl iodide with Sodium metal in ether. This is an example of a Wurtz coupling reaction. Here, the two moles of alkyl halides react with sodium metal in presence of ether to give alkanes. The reaction can be given as: $2C{H_3}I + Na\xrightarrow{{ether}}C{H_3} - C{H_3}$
It gives ethane as the product. Hence option A is incorrect.
B) Hydrogenation includes the addition of Hydrogen across an unsaturated bond. Hydrogenation of alkene gives alkanes, and hydrogenation of alkynes gives alkenes. This most commonly used catalyst is ${H_2}/Pd - C$ . Alkene is first adsorbed on the surface of metal, and then it reacts with Hydrogen. The reaction of Hydrogenation of Ethene can be given as: $C{H_2} = C{H_2} + {H_2}\xrightarrow{{Pd/C}}C{H_3} - C{H_3}$Hence option B is incorrect.
C) Electrolysis of sodium acetate on electrolysis gives us carbon dioxide, ethane, hydrogen and sodium hydroxide. Ethane is formed at the anode. The reaction can be given as:
$2C{H_3}COONa + 2{H_2}O \to C{H_3} - C{H_3} + NaOH + C{O_2} + {H_2}$
This option is incorrect.
D) This reaction is an irreversible reaction and on hydrolysis of aluminium carbide gives Methane and aluminium hydroxide. This is a laboratory method for formation of methane. The reaction can be shown as: $A{l_4}{C_3} + 12{H_2}O \to 4Al{(OH)_3} + 3C{H_4} \uparrow$
This is the correct option.

Hence the correct option is Option (D),

Note:
The hydrogenation of ethene is majorly used in the oil and food industry for converting unsaturated oil/fat to saturated oil/fat. This process helps to increase the shelf life of the oil. Hydrolysis of carbides gives a variety of saturated molecules like magnesium carbides on hydrolysis gives propane.