Question

Which one of the following is used as a test for aliphatic primary amines?
A) Tollen’s test
B) Fehling’s test
C) Isocyanide test
D) Azo dye test
E) Phthalein fusion test

Answer 1

Amines are compounds containing amine groups having nitrogen atoms with lone pairs. Aliphatic amines are the amine with the absence of an aromatic ring in their structure. As the amines are the derivatives of ammonia there are three main types of amines which are primary, secondary, and tertiary amines.

Complete step-by-step answer:
The amines in which one of the hydrogen atoms of the ammonia is replaced by the alkyl group are known as aliphatic primary amines. The general representation of the primary aliphatic amines is as follows:

Here, option (A) is given as Tollen’s test also called a silver mirror test. Tollen’s test is used to distinguish the aldehydes and ketones. Therefore, option (A) is an incorrect answer to the question.

Now, option (B) given is Fehling’s test. It is one of the important tests used to distinguish the aldehydes and ketones, also used for reducing and non-reducing sugars. Therefore, option (B) is an incorrect answer for the given question.

Now, option (C) given is the Isocyanide test. In this test, the analyte is heated with a mixture of alcoholic potassium hydroxide and chloroform. This test is used for the primary amines in which primary amines are converted into the isocyanide that is carbylamines detected by its foul smell. Hence, the option (C) Isocyanide test is the correct answer for the given question.

The Azo dye test is one of the important tests used for the identification of aromatic amines. Therefore, option (D) is an incorrect answer for the given question.

The phthalein fusion test is used for the detection of the phenol functional group in the analyte. Therefore, option (E) is an incorrect answer for the given question.

Hence the correct answer is option ‘C’.

Note: As the amines are derivatives of the ammonia, three main types of the amines are as follows:

1. Primary amines: These are the amines in which one of the hydrogen atoms of the ammonia is replaced by the alkyl or aryl group.

2. Secondary amines: These are the amines in which two of the hydrogen atoms of the ammonia are replaced by the alkyl or aryl group.

3. Tertiary amines: These are the amines in which all three hydrogen atoms of the ammonia are replaced by the alkyl or aryl group.