Question

A secondary amine is
(a) a compound with two \[ - N{H_2}\] groups.
(b) a compound with 2 carbon atoms and a \[ - N{H_2}\] group.
(c) a compound with a\[ - N{H_2}\]on the carbon atom in the number 2 position.
(d) a compound in which 2 of the hydrogen of \[N{H_3}\]have been replaced by alkyl or aryl groups.

Answer 1

Hint: Amines are belonging to the class of organic molecules, which contains nitrogen atoms. Amines are formed by the replacement of one or more hydrogen atoms of ammonia molecules (\[N{H_3}\]) by the alkyl and aryl groups.

Complete step-by-step answer:
Amines are present in various biomolecules such as proteins, vitamins, hormones, etc. They are also used in industries for making detergents and various kinds of drugs.
Amines are derivatives of ammonia. Depending upon the number of alkyl or aryl groups, the amines can be classified as primary (\[{1^ \circ }\]), secondary (\[{2^ \circ }\]), and tertiary (\[{3^ \circ }\]).
Primary (\[{1^ \circ }\]): If only one alkyl or aryl group is attached to the nitrogen atom of ammonia then it is called Primary or \[{1^ \circ }\] amine.

Image: General structure of primary amine, where R represents the aryl and alkyl group.
Secondary (\[{2^ \circ }\]): If two alkyl or aryl groups are attached to the nitrogen atom of ammonia then it is called secondary or \[{2^ \circ }\]amine.

Image: General structure of secondary amine, where R represents the aryl and alkyl group.
Tertiary (\[{3^ \circ }\]): If three alkyl or aryl groups are attached to the nitrogen atom of ammonia then it is called tertiary or \[{3^ \circ }\] amine.

Image : General structure of tertiary amine, where R represents the aryl and alkyl group.
The naming of amines:
According to IUPAC the naming of aliphatic amines can be done by writing the name alkyl before the name of amine and therefore the name of amine will be alkylamine i.e., alkyl part + amine =methylamine.
For example, The IUPAC name of \[C{H_3}N{H_2}\] can be done by adding the name of the alkyl group i.e., \[ - C{H_3}\] group before the name of amine. Hence the name of \[C{H_3}N{H_2}\]will be methylamine.
In the case of secondary (\[{2^ \circ }\]) and tertiary (\[{3^ \circ }\]) amine, the prefixes di and tri are used before the name of the alkyl group.

Hence, from the above statements, option (d) will be the correct answer.

Note: In some cases, the amines contain more than one amino group. Then the location of the amino group is defined by the numbering of the carbon atoms in the parent chain. The numbering will start from where the carbon atom bearing \[ - N{H_2}\] group get the lowest numbers. Therefore, prefixes along with the number of amino groups and their position in the molecule.
For example, \[N{H_2} - C{H_2} - C{H_2} - N{H_2}\] can be named as ethane 1, 2-diamine.