Question

${H_3}C - N{H_2} + NaN{O_2} + HCl \to A$
${C_6}{H_5} - N{H_2} + NaN{O_2} + HCl \to B$
Reactions proceed in two different paths. Complete the above reaction.

Answer 1

Hint: By looking at the reactions, we might guess that a diazonium salt is formed in the reaction. In this reaction, a primary amine reacts with Sodium nitrite and hydrochloric acid.

Complete step by step answer:
In the first reaction, there will be formation of diazonium salt of methyl amine. But being unstable it will react vigorously with the water present and produce methanol as the major product.
The chemical equation for the same is illustrated below:
${H_3}C - N{H_2} + HCl \to C{H_3}N = NCl + {H_2}O \to C{H_3}OH + HCl + {N_2}$
The reaction of aniline with Sodium nitrite and hydrochloric acid is illustrated below; the product of the reaction is benzene diazonium chloride. The compound formed is soluble in water but reacts with it only when warmed. The diazonium group has application in many industries. From dyes and pigment industry to synthesis of various organic compounds, this combination of organic and inorganic components has been a blessing for the scientists. We should note that the reactions involving a diazonium salt are always done with a freshly prepared solution made in this way. Diazonium salts are extremely unstable and tend to be very explosive as solids.
${C_6}{H_5} - N{H_2} + NaN{O_2} + HCl \to {C_6}{H_5}{N^ + } - Cl + NaCl + 2{H_2}O$

Additional information:
The most widely practiced reaction of diazonium salts is azo coupling. In this process, the diazonium compound is attacked by, i.e., coupled to, electron-rich substrates.

Note: Diazonium compounds are standard reagents used in synthesis of organic compounds, especially aryl derivatives. But the first use of diazonium salts was to produce water-fast dyed fabrics by immersing that fabric in an aqueous solution of the diazonium compound, followed by immersion of the same in a solution of the electron-rich ring that undergoes electrophilic substitution.