Question

How will you convert (i) chloroethane to butane (ii) Methylamine to methyl isocyanide?

Answer 1

We know that the Wurtz reaction is the reaction of alkyl halides. So we can solve the (i) question with the Wurtz reaction. And in the second part of question we use formation reaction of isocyanides from the amies i.e. Carbylamine reaction.

Complete step by step answer:
In organic chemistry, the Wurtz reaction is a coupling reaction of alkyl halides. It is used for the formation of higher alkanes containing even numbers of carbons atoms. In this reaction, two alkyl halides are treated with the sodium metal in the dry ether solution. We use this reaction for formation of symmetrical alkanes. General form of the this reaction is written as: (in the presence of ether solution):
$2R - X + 2Na \to R - R + 2NaX$

For the given question (i), reaction is given below, for the conversation of chloroethane$\left( {{C_2}{H_5}Cl} \right)$ to butane $\left( {{C_4}{H_{10}}} \right)$
$2{C_2}{H_5}Cl\xrightarrow[{dryether}]{{2Na}}{C_4}{H_{10}} + 2NaCl$

The carbylamine reaction is the test for primary amines. In this reaction primary amine, chloroform and base is used for the formation of isocyanide. General form of this reaction equation can be written as:
$R - N{H_2} + CHC{l_3} + 3KOH\xrightarrow{\Delta }R - NC + 3KCl + 3{H_2}O$

Methylamine is a primary amine which gives a foul-smelling compound but ${2^0},{3^0}$ amines would not have enough hydrogen for the reaction. For the conversation of methylamine to methyl isocyanide, reaction is given below:
$C{H_3}N{H_2} + CHC{l_3} + KOH \to C{H_3}NC + 3KCl + 3{H_2}O$

Note: We know that Wurtz reaction is the basic reaction which is used for the formation of alkane which have a higher number of carbon atoms than the reactant have. The mechanism of this is a free radical mechanism. The carbylamine reaction is a test reaction which is also known as Hoffman isocyanide synthesis. This reaction has an intermediate which is known as dichlorocarbene.