Maharashtra Board Class 12 Chemistry Chapter 13 Amines PDF Download

13 Amines

Amines are nitrogen containing organic compounds having basic character. Amines are present in structure of many natural compounds like proteins, vitamins, hormones and many plant products like nicotine.

13.1 Classification Of Amines

Amines are classified as primary (1°), secondary (2°) and tertiary (3°) amines. Their structures are obtained in simple way by replacing one, two or three hydrogen atoms of NH\(_3\) molecule by alkyl/aryl groups.

Secondary and tertiary amines are further classified as simple / symmetrical amines and mixed / unsymmetrical amines. When all the alkyl or aryl groups on nitrogen are same, it is a simple amine. If these groups are different, then the amine is a mixed amine.

Amines are also divided into two major classes, namely, aliphatic and aromatic amines on the basis of nature of the groups attached to the nitrogen atom.

Teacher's Note

Amines have a lone pair of electrons on nitrogen which makes them basic. In your daily life, you can smell amines in fish and meat because they contain natural amines.

Exam Trick

Remember: Primary amine has one R group on nitrogen, secondary has two R groups, and tertiary has three R groups. Think like this - 1° = 1 R, 2° = 2 R, 3° = 3 R.

Points To Remember

Amines are basic organic compounds with nitrogen atom.
Primary amines have -NH\(_2\) group attached to carbon.
Secondary amines have two alkyl groups on nitrogen.
Tertiary amines have three alkyl groups on nitrogen.
Aromatic amines have amino group attached to benzene ring.

13.2 Nomenclature Of Amines

13.2.1 Common Names

Common names of aliphatic amines are given by writing the name of alkyl group followed by suffix-amine, that is, 'alkyl amine'. In the case of mixed amines, the names of alkyl groups are written in alphabetical order. If two or three identical alkyl groups are attached to nitrogen atom, the prefix 'di-' or 'tri-' is added before the name of alkyl group. The parent arylamine, C\(_6\)H\(_5\)-NH\(_2\), is named as aniline. Other aromatic amines are named as derivatives of aniline.

13.2.2 IUPAC Names

In IUPAC system, primary amines are named by replacing the ending 'e' of the parent alkane by suffix -amine (alkanamine). A locant indicating the position of amino group is added before the suffix amine. When two or more amino groups are present, the prefix 'di-', 'tri-' etc. are used with proper locant. In this case the ending 'e' of parent alkane is retained.

Secondary or tertiary amines are named as N-substituted derivatives of primary amines. The largest alkyl group attached to nitrogen is taken as the parent alkane and other alkyl groups as N-substituents. While naming arylamines ending 'e' of arene is replaced by 'amine'. The common name of aniline is also accepted by IUPAC.

Teacher's Note

Learning amine names is like learning a simple language. Primary amine = one side chain, secondary = two, tertiary = three. In India, this naming system is used in chemistry books and competitive exams like JEE.

Exam Trick

Remember: For IUPAC names of primary amines, just replace the last 'e' of the alkane with 'amine'. For example, ethane becomes ethanamine, propane becomes propanamine. This is your shortcut.

Points To Remember

Common names use 'amine' suffix after the alkyl group name.
In mixed amines, write alkyl groups in alphabetical order.
For multiple same groups, use di- or tri- prefix.
IUPAC names replace alkane ending 'e' with 'amine'.
Aniline is the parent name for aromatic amines.

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