Question

How will you convert the following?
Ethyl bromide to ethyl isocyanide

Answer 1

Isocyanide molecules are only formed on reaction with alcoholic silver cyanide otherwise with other cyanides the form cyanide molecules.

Complete answer:
Conversion of ethyl bromide to isocyanide:
Ethyl bromide can be converted to ethyl cyanide by various means but there is only one typical way to convert ethyl bromide to ethyl isocyanide that is by reacting ethyl bromide with alcoholic silver cyanide.
Ethyl bromide when mixed with alcoholic silver cyanide it gives ethyl isocyanide and silver bromide is formed.
Chemical formula of ethyl bromide is: $C{{H}_{3}}\,C{{H}_{2}}\to Br$
Chemical formula of silver cyanide is: $AgCN$
Chemical formula of ethyl isocyanide is: $C{{H}_{3}}\,C{{H}_{2}}\to NC$
Chemical formula of silver bromide is: $AgBr$

Overall reaction is:
Ethyl Bromide + Silver cyanide → Ethyl Isocyanide + Silver Bromide

$CHCH-Br\text{ }+\text{ }AgCN\text{ }\to \text{ }CHCH-NC\text{ }+\text{ }AgBr$

The reason why is the only compound that form isocyanide is because $AgCN$ has higher covalent character therefore in silver cyanide lone pair is more clouded over nitrogen instead of carbon so the bond is made by nitrogen and in comparison with the other compounds like $NaCN$ & $KCN$lone pair is more crowded over carbon rather than nitrogen so the bond is formed through carbon.

Note: Ethyl bromide is converted to ethyl isocyanide by the reaction of ethyl bromide with silver cyanide. It does not form with sodium cyanide or potassium cyanide as in them lone pair is present on carbon unlike silver cyanide in which lone pair is present on nitrogen rather than carbon. Therefore, for the formation of isocyanide reaction is done with alcoholic silver cyanide not with any other cyanide compound.