Question

In the reaction

The compound ‘A’ is
(A) $RCON{{(Me)}_{2}}$
(B) $RCON{{H}_{2}}$
(C) $RCONHMe$
(D) ${{(RCO)}_{2}}NH$

Answer 1

Hint: Amines are functional groups containing nitrogen atoms with a lone pair. Its structure resembles ammonia ($N{{H}_{3}}$ ) but in amines, one or more hydrogen can be replaced by an alkyl or aryl group. In other words, amines are the derivatives of ammonia. Acetyl chloride is a derivative of carboxylic acids.

Complete Step by Step Solution:
This reaction involves a reaction between two functional groups—amine and an acyl group.
Firstly, we should understand the nature of the functional groups involved. The amine involved in this reaction is dimethyl amine. It is a secondary amine. These amines are basic in nature due to the presence of electron-releasing alkyl groups on the nitrogen atom. These electron-releasing groups shift the electron density on nitrogen atoms, and thus, make the electrons on nitrogen available for protonation of acid. The acyl halide contains a carbonyl group.

The reaction between acyl chloride and dimethyl amine is known as aminolysis of acid chloride. It is a nucleophilic addition/elimination reaction. It proceeds through the removal of the chlorine atom from the acetyl molecule. The amine group then gets attached to the acetyl group by replacing H with the acetyl group. This reaction forms an amide. Along with an amide, the $HCl$ is also formed as a side product.

The reaction is as shown:

In this reaction, N,N-dimethylamide ($RCON{{(Me)}_{2}}$) is formed.
Correct Option: (A) $RCON{{(Me)}_{2}}$

Note: The side product $HCl$ formed in this reaction is formed by $H$ from dimethyl amine and $Cl$from acyl chloride. However, if amine is present in excess in the reaction, then the $HCl$formed in the reaction will again react with the amine to form alkyl ammonium chloride.