Organic Compounds Containing Nitrogen

Organic compounds containing nitrogen, sometimes known as amines, are created by substituting an alkyl or aryl group for one or more hydrogen atoms in ammonia. They can be found in nature in a variety of forms, including proteins, vitamins, hormones, and so on. These amines are vital for our bodies in the form of amino acids. The IUPAC system dictates that amines are named by first identifying the alkyl group and then adding amine at the end, such as methylamine. 2-Bromoaniline is an example of an aromatic amine called after the derivative of the simplest aromatic amine, aniline.

Here, we will discuss the different structures of amines, their physical qualities and chemical reactions. We see amine compounds in bulk form in real life, but we rarely inquire about their synthesis.

Structure of amines

The nitrogen in amines is sp3 hybridised, with three sigma bonds and one lone pair of electrons. Amines have a tetrahedral geometry, however, the bond angle in their structure is always less than 109.50 degrees due to the lone pair of electrons on the nitrogen atom, which lessens the bond angle.

Preparation of amines

The following procedures can be used to make amines:

• Reduction of nitro compounds: The (H2 / Pd) reagent reduces the nitro compounds to amines in this reaction.
• Reduction of nitriles: Nitriles are reduced to amines in this process by another strong reducing agent, (H2 / Ni).
• Hoffmann bromamide degradation reaction: The amide is treated with bromine in the presence of an aqueous solution of NaOH in this reaction. The amide is converted to a primary amine with one carbon less than the amide in this reaction.

Physical properties

• Lower aliphatic amines are gaseous compounds with a fishy odour, while higher aliphatic amines are liquids.
• Lower aliphatic amines are water-soluble due to their propensity to form hydrogen bonds with water molecules.
• Amines can be dissolved in organic solvents including alcohol, ether, and benzene.

The boiling points of amines are listed in the following order:

Primary > Secondary> Tertiary

Primary amines have more intermolecular contact than secondary amines, while tertiary amines have no intermolecular interaction.

Chemical reactions

• Alkylation of amines: Amines react with alkyl halides in this reaction. This reaction produces a 10% higher amine.
• Acylation of amines: Anhydrides react with amines in this reaction, yielding amide as a result.
• Carbylamine reaction: The result of this reaction is isocyanides, which are generated when primary amines react with chloroform in the presence of potassium hydroxide.
• Reaction with nitrous acid: Under this reaction, amines react with nitrous acid to produce diazonium salt or alcohol, depending on which type of amine is involved.

Uses of amines

In drug production, aliphatic amines are utilised as intermediates. Aromatic amines, such as aniline and its derivatives, are used to make colours, pharmaceuticals, and photographic developers. All hair dyes contain 1,4-diaminobenzene as the major component. Herbicides made from dithiocarbonates, which are chemicals produced from primary amines, are widely used.

Important points to remember

• Amines are considered ammonia derivatives. Based on how many alkyl groups have replaced the hydrogen atoms in ammonia, they are classed as primary, secondary, or tertiary.
• When alkyl halides react with ammonia, they form a combination of primary, secondary, and tertiary amines as well as quaternary ammonium ions.
• The carbylamine reaction can distinguish primary amines from secondary and tertiary amines.
• Aliphatic primary amines diazotize to generate alcohols, while aromatic primary amines diazotize to form diazonium salts.
• The amino group (–NH2) is an electrophilic aromatic substitution reaction activator and ortho-, para-directing group.
• The reaction of alkyl halides with alcoholic silver nitrite produces nitroalkanes.
• Nitrobenzene is made by nitrating benzene with concentrated HNO3 in the presence of concentrated H2SO4.
• In an acidic media, primary nitroalkanes hydrolyze to yield carboxylic acids, whereas secondary nitroalkanes give ketones.

Conclusion

Amines are chemical molecules that contain and are often based on one or more nitrogen atoms. Amines are structurally similar to ammonia in that the nitrogen atom can join up to three hydrogens, but their carbon connection gives them extra features.