Question

Isocyanide test can be performed in the fab to identify a primary amine at room temperature. However, teacher 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 is the azo dye test preferred over isocyanide test?
b.Why controlled conditions like zero degree centigrade are needed in azo dye test.
c.What values are reflected by the above choices?
d.Write chemical reaction for coupling reaction.

Answer 1

Hint – Here we will proceed by explaining the Isocyanide test for primary amines to treat with chloroform we can solve this question.

Complete answer:

It is also known as Saytzeff’s Isocyanide test. In this reaction, the analyte is heated with alcoholic potassium hydroxide and chloroform. If a primary amine is present, the isocyanide (carbylamine) is formed, as indicated by a foul odour.
(a). This test is positive 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 given by aniline but not by $N - $ methylaniline.
$RN{H_2} + 3KOH + CHC{l_3} \to RNC + 3KCl + 3{H_2}O$
(b). In aqueous solution diazonium salts are unstable at temperature uses above five degrees centigrade, diazonium salts have been known to decompose, often explosively to liberate nitrogen gas temperatures to low however can cause later on.
(c ). The reactions will go forward at room temperatures.
(d). The mechanism involves the addition of amine to dichlorocarbene, a reactive intermediate generated by the dehydrohalogenation of chloroform. Two successive base-mediated dehydrochlorination steps result in formation of the isocyanide.

Note – Whenever we come up with this type of question, one must know that Isocyanide test (Carbylamine reaction) is always given by primary amines, it is not given by secondary or tertiary amines. Every primary amines is a carbylamine reaction for example $\left( {Ph - C{H_2} - N{H_2}} \right)$ is an example of Benzylamine reaction, it also comes under the category of primary amines that is isocyanide test.