Amine’s Properties

Amines are organic compounds derived from ammonia. Ammonia derivatives are formed when an alkyl/aryl group replaces one or more hydrogen atoms of ammonia. These compounds are functional in making polymers, dyestuff, and drugs. Amino acids, trimethylamine, aniline and biogenic acids are a few examples of specific amines. 

The organic compound amine is classified into four major types: primary, secondary, tertiary and cyclic. Here is an overview of the properties of different types of amines. 

What are the different types of amines?

 All forms of amines act differently from each other. They are formed by replacing hydrogen atoms with an alkyl/aryl group. Following is the description of the types of amines:

• Primary Amines: Primary amines are obtained when the aromatic group replaces only one out of three hydrogen atoms of ammonia. Examples of primary amines are alkylamines and methylamine (CH3NH2). 
• Secondary Amines: Secondary Amine is a second major part of the organic amine compound, containing two organic substituents, such as alkyl or aryl. Both substituents are attached to nitrogen and one hydrogen atom. 
• Tertiary Amines: Three nitrogen atoms consist of three organic substituents in tertiary substituents. Examples of tertiary amines are trimethylamine N(CH3)3, which has a fish-like smell and Ethylenediamine tetra-acetic acid (EDTA), which contains two amine groups and a lone pair of electrons. 
• Cyclic Amines: A Cyclic amine is an aromatic ring structure’s secondary or tertiary amine. A cyclic amine has a three-membered ring aziridine (C2H5N) and six-membered ring piperidine. An example of cyclic Amine is N-methyl-piperidine (CH2)5NH.

Properties of amines 

Amine compounds show intermolecular interactions by forming hydrogen bonds. Thus, they show properties such as water solubility and elevated boiling points. Generally, the amine structure consists of a nitrogen atom with a lone pair of electrons and three specific substituents. Nitrogen can link with four substituents, resulting in a positive charge. 

The properties of amines are classified into two types:

• Physical properties 
• Chemical properties 

Physical properties

Amines share higher hydrogen boiling points of their hydrogen compounds than phosphines. They also show water solubility. This property is adversely affected as the number of carbon atoms in the amine compound increases. 

Meanwhile, aliphatic amines dissolve in water in organic polar events. The aromatic amines share their pair of electrons, resulting in reduced hydrogen bonding. Their water-solubility and high boiling points also decrease in the chemical process. 

Some other physical properties of amines are listed below:

• The lower aliphatic amines’ property consists of a fishy smell and is often gaseous.
• Primary amines containing 3-4 carbon atoms are liquids at room temperature. However, it soon converts into solid form at a higher temperature. 
• Usually, aniline and arylamines are colourless. However, the amine parts get coloured when stored at an open place owing to atmospheric oxidation. 
• The lower aliphatic amines can form hydrogen bonds with water molecules. Hence, they are soluble in water. 
• An increase in the part of hydrophobic alkyl results in an increase in molar mass amines, decreasing its solubility in water. 
• Often, higher amines are unsolvable in water. Therefore, organic solvents such as benzene, ether and alcohol dissolve amines quickly. 
• Alcohols benzene are organic solvents that can more easily dissolve in water than amines. Since they develop higher polarity than the ammonia compound, they are more likely to form strong intermolecular hydrogen bonds.
• Primary and secondary amines are employed in intermolecular interaction for hydrogen bonding. Nitrogen and hydrogen form a bond with their molecules. 
• Primary amines have two hydrogen atoms present in themselves, which allows them to grow pre-eminent intermolecular association than from secondary amines. Due to the unavailability of free hydrogen atoms, tertiary amines cannot form intermolecular associations while bonding. 
• Based on their boiling points, amines are arranged as primary > secondary > tertiary. 

Chemical properties 

Often, amines turn reactive owing to the presence of lone pairs of electrons in nitrogen atoms and different electronegativity levels between hydrogen and nitrogen atoms. The number of hydrogen atoms that connect with the nitrogen direction of amines. As a result, all primary, secondary and tertiary amines form different reactions and properties. Therefore, the amines act as nucleophiles and obtain a lewis base, following the availability of an undistributed pair of electrons. Below are some chemical properties of amines you can study:

• Amines can form salts by reacting with various acids like hydrochloric acid to form ammonium salts. 
• The treatment of ammonium salt with a base like NaOH (sodium hydroxide) is often helpful in reviving parent amine.
• Amine salts are insoluble in organic substituents such as ether but soluble in water. 
• These nitrogen compounds react with mineral acids and form ammonium salts. 
• Amines form Lewis bases as there are unshared pairs of electrons in nitrogen atoms. 

Conclusion

The properties of amines are of physical and chemical types. The physical properties explain the boiling point and intermolecular interaction of ammonia forms with hydrogen atoms. The chemical properties of amines describe the electronegativity levels and unshared pair of electrons in nitrogen atoms as it gets attached to hydrogen. The only difference between the two amines’ properties is that physical properties observe the actions without any chemical change. The other chemical amines’ properties follow when any ammonia derivative undergoes a chemical change with other compounds. Hope this has helped you get an overview of the amine properties.