Q.Explain why simple aliphatic amines such as $\text{CH}_3\text{NH}_2$ show optical inactivity even when nitrogen is bonded to three different groups plus a lone pair (four 'different' groups around nitrogen, as in a stereocentre).

Amines are classified 1°/2°/3° by the number of alkyl/aryl groups replacing the H atoms of NH3.

• n-propylamine, CH3CH2CH2NH2: one alkyl group -> 1°
• Isopropylamine, (CH3)2CHNH2: one alkyl group -> 1° …

Nitrogen in an amine has four electron domains (3 bonding pairs + 1 lone pair), which arrange tetrahedrally, corresponding to sp3 hybridisation.

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Like other amines, trimethylamine's N atom is sp3 hybridised with 3 bond pairs (to the 3 methyl groups) and 1 lone pair, giving a pyramidal (trigonal pyramidal) molecu …

A primary amine has exactly one alkyl/aryl group attached to nitrogen, with the remaining two bonds to hydrogen, giving the -NH2 functional group.

Amines are classified by how many H atoms of NH3 are replaced by alkyl/aryl groups: primary amines (R-NH2, one substitution), secondary amines (R2NH, two substitution …

A primary amine has the general formula $R\text{-}NH_2$.

Amines are derivatives of ammonia ($NH_3$) obtained by replacing one, two or three hydrogen atoms with alkyl/aryl groups, giving primary, secondary and tertiary amines respectively. A primary amine has only ONE hydrogen of ammonia replaced by an alkyl or aryl (R) group, s …