Question

How is ethylamine prepared from methyl iodide?

Answer 1

To answer this question, you should recall the concept preparation of amines from haloalkanes. A primary amine is formed when alkyl halide reacts with ammonia. This can be used further to produce other substituted amines.

Complete Step by step solution:
Ethylamine is a colourless/light yellow liquid with a strong ammonia-like odour and is used in the preparation of various pharmaceutical products. It condenses just below the room temperature to a liquid miscible with mostly all solvents. It acts as a nucleophilic base. Let us discuss the easiest procedure to form ethylamine from methyl iodide
1.Methyl iodide is treated with $NaCN$ to form acetonitrile
$C{H_3} - I + NaCN \to C{H_3} - CN + NaI$
This is an example of $S{N^2}$ a reaction
-$S{N^2}$ reactions are bimolecular reactions in which there are simultaneous bond-making and bond-breaking steps.
-$S{N^2}$ reactions do not proceed via an intermediate.
-$S{N^2}$ reactions result in inverted stereochemistry at the reaction centre.
-Steric effects are particularly important in $S{N^2}$reactions.

2.Acetonitrile is reduced with Na/ ethanol to form ethylamine. This reaction is called Mendius reduction
$C{H_3} - CN \to C{H_3} - C{H_2} - N{H_2}$(in presence of Na/Ethanol)

Additional Note: Ethylamine can also be synthesised from the reaction of ethane and ammonia in the presence of a basic catalyst. Ethylamine is a weak base and undergoes reactions like acetylation and protonation. It can also be oxidised to form acetaldehyde.

Note: Another way of preparing ethyl amine prepared from methyl iodide is by using cyanohydrin reduction. Methyl iodide first is converted into methyl chloride using the ion-exchange method: $C{H_3}I{\text{ }} + {\text{ }}NaCl{\text{ }} \to C{H_3}Cl\; + {\text{ }}NaI$.
Now the second reaction can be performed: