Question

Isocyanide test can be performed in the fab to identify a primary amine at room temperature. However, teachers always recommend carrying out azo dye test although it requires more time and effort with special conditions like zero degrees centigrade, Contextual questions
(a) Why azo dye test is preferred over isocyanide test?
(b) Why controlled condition like zero degree centigrade is needed in azo dye test.
(c) What values are reflected by the above choices?
(d) Write chemical reaction for coupling reaction.

Answer 1

$\left(a\right)$ This test is possitive for primary amines$.$ The test is known as isocyanide test because isocyanides are produced when a primary amine is treated with chloroform in presence of alkali$.$ This is also given by aniline but not by $N$-methylamilin$.$

$RN{H}_2+3KOH+CH{Cl}_3\to RNC+3KCl+3H_{2}O$

$\left(b\right)$ In aqueous solution diazonium salts are unstable at temperature usues above five degree centigrade$.$ At temperature above five degree centigrade $,$ diazonium salts have been known to decompose$,$ often explosively to liberate nitrogen gas temperetures to low however can cause crystallisation$,$ which causes later on$.$

$\left(c\right)$ The reaction will go forward at room temperatures$.$

$\bullet$This reaction and step $\left(d\right)$ are given to the image$.$