Question

Which will not go for diazotization ?

• A. $C _{6} H _{5} NH _{2}$
• B. $C _{6} H _{5} CH _{2} NH _{2}$
• C.
• D.

Answer 1

Answer: (B)

$C _{6} H _{5} CH _{2} NH _{2}$

Answer 2

Only $1^{\circ}$ aromatic amine (primary aromatic amine) form diazonium salts at low temperature $\left(0^{\circ}-5^{\circ} C \right)$. A reaction in which $- NH _{2}$ group is converted into diazo group $(-\overset{+}{ N } \equiv= N )$ is called diazotisation. Diazotised salts are stable in cold aqueous solution.
$C _{6} H _{5} NH _{2}+ HCl{->[{0^{\circ}-5^{\circ} C }]} C _{6} H _{5} N\overset{+}{H _{3}} Cl ^{-}$
$NaNO _{2}+ HCl{->[{0^{\circ}-5^{\circ} C }]} HNO _{2}+ NaCl$
$C _{6} H _{5} \overset{+}{N}H _{3} Cl ^{-}+ HNO _{2}{->[{0^{\circ}-5^{\circ} C }]}C _{6} H _{5} \overset{+}{ N }_{2} Cl ^{-}+2 H _{2} O$

aromatic primary amines, so undergo diazotisation but $C _{6} H _{5} CH _{2} NH _{2} \quad$ (aliphaticamine) will not undergo diazotisation.