Question

What would be the product for the following reaction?

A. $Ph - Cl$
B. $Ph - {N_2}$
C.

D.

Answer 1

Hint: Since it is tertiary aromatic amines that means there is no N-H bond s nitrosylation on nitrogen and salt formation is not possible. This reaction is used for the distinction of primary, secondary and tertiary amines.

Complete step by step answer: In this reaction, there is electrophilic substitution at the para position. Below are the steps involved in the reaction:

Step1: Sodium nitrite reacts with hydrochloric acid to form sodium chloride and nitrous acid. The reaction for this step is written as:

$
  NaN{O_2} + HCl \to NaCl + HN{O_2} \\
    \\
$
Step2: This is the protonation step, below is the reaction that shows protonation

$H\mathop O\limits_{..}^{..} N = O + {H^ + } \to {H_2}\mathop O\limits_{..}^ + N = O$

Step 3: This step involves the formation of the nitrosonium ion. Since the oxygen atom is one of the most electronegative atoms, so + charge on it makes it unstable so it withdraws the electrons from the nitrogen atom and forms water and nitrosonium ion $\mathop N\limits^ + = O$.

Step 4: In this step, nitrosonium ion attacks on N, N-dimethylaniline to give N, N-dimethyl-p-nitrosoaniline as the main product.
So, the correct answer is “Option C”.

Additional Information: Electrophilic substitution reactions are that chemical reaction in which an electrophile displaces a functional group in a compound. There are mainly two types of electrophilic reaction:
- Electrophilic aromatic substitution reaction
- Electrophilic aliphatic substitution reaction.
- There are some important reactions of Electrophilic aromatic substitution type that take place are aromatic nitration, aromatic halogenation, aromatic sulfonation, and friedel craft reactions.

Note: Here, the dimethylaniline group activates the benzene ring at ortho and para position. But the steric hindrance of the bulkier group does not attack the ortho position. As a result, the compound formed is known as P-nitrosodimethylaniline. It is a dark green crystalline solid and is insoluble in water.