Organic Compounds Containing Nitrogen – JEE Mains Chemistry
1. General Introduction to Organic Compounds Containing Nitrogen
Organic compounds containing nitrogen include amines, diazonium salts, and their derivatives. Nitrogen is an essential element in organic chemistry and plays a vital role in many biological molecules, including proteins and nucleic acids.
2. Amines
Amines are organic compounds that contain nitrogen atoms bonded to one or more alkyl or aryl groups. Amines are classified based on the number of alkyl or aryl groups attached to the nitrogen atom.
- Nomenclature of Amines: Amines are named based on the alkyl or aryl groups attached to the nitrogen atom, followed by the suffix '-amine'. For example, methylamine (CH₃NH₂) and aniline (C₆H₅NH₂).
- Classification of Amines: Amines can be classified as primary (one alkyl group attached to nitrogen), secondary (two alkyl groups attached to nitrogen), or tertiary (three alkyl groups attached to nitrogen).
- Structure of Amines: Amines have a pyramidal structure with sp³ hybridization at the nitrogen atom. The bond angles are slightly less than 109.5° due to the lone pair of electrons on nitrogen.
- Basic Character: Amines are basic in nature because the lone pair of electrons on the nitrogen atom can accept a proton (H⁺). The basicity of amines depends on the electron-donating or electron-withdrawing effects of the substituents attached to the nitrogen.
- Identification of Amines: Amines can be identified by reactions such as the formation of ammonium salts, or through the detection of a foul smell in the case of lower amines.
3. Diazonium Salts
Diazonium salts are compounds containing a positively charged nitrogen atom bonded to an aryl group (C₆H₅N₂⁺). These salts are important intermediates in synthetic organic chemistry, especially in the synthesis of aromatic compounds.
- Formation of Diazonium Salts: Diazonium salts are typically prepared by reacting aromatic amines with nitrous acid (HNO₂) at low temperatures. For example, aniline reacts with nitrous acid to form the diazonium ion (C₆H₅N₂⁺).
- Importance in Synthetic Organic Chemistry: Diazonium salts are highly reactive intermediates and are used in the formation of a wide variety of aromatic compounds through reactions such as coupling, halogenation, and nitration.
- Coupling Reactions: Diazonium salts undergo coupling reactions with aromatic compounds to form azo compounds, which are widely used as dyes.
- Electrophilic Substitution Reactions: Diazonium ions undergo electrophilic substitution reactions with various nucleophiles, leading to the formation of substituted aromatic compounds.