Physical Properties of Amines

Have you ever wondered why the smell of a toilet is so unbearable? The smell is caused by  amines, which are the products of ammonia. Despite their unpleasant odour, Chemistry and our daily lives are heavily dependent on these molecules. Organic molecules that include amines are vital. In addition to being a fascinating topic of study, amines also have a wide range of practical applications in biology. Nitrogen is the sole well-known by-product. However, the number of hydrogen atoms in ammonia can be changed to produce several different compounds.

Amines are ammonia derivatives in which groups including aryl or alkyl replace one or more hydrogen atoms.  Amines are composed of nitrogen atoms with only one pair of electrons and organic molecules with functional groups that contain nitrogen atoms. Examples of amines include amino acids, biogenic amines, trimethylamine, and aniline.

Types of Amines

The different types of amines include cyclic, primary, secondary, and tertiary. To make an amine primary, you must remove one of the three hydrogens. When three of the three hydrogen atoms are replaced, we get a secondary amine, and when all three hydrogen atoms are replaced, we get a tertiary amine. Only tertiary or secondary amines can be cyclic, such as aziridine, which has a three-member ring.

Primary, secondary, tertiary, and cyclic amines are all different types of amines. A primary amine is one in which an alkyl or aryl group is substituted for one of the three hydrogen atoms. A secondary amine is formed when two of the three hydrogen atoms are substituted. Tertiary amines are  generated when all three hydrogen atoms are substituted. It is important to keep in mind that only secondary or tertiary amines are cyclic.

Physical Properties of Amines

1.     Lower aliphatic amines are of a  fishy odour and  are gaseous in nature. Primary amines have more than equal to 3 or 4 carbon atoms which are  liquid in nature at normal temperature. However, amines at higher temperature are solids.
2.   While aniline and other arylamines are usually colourless,but If left out then, atmospheric oxidation causes them to turn brown .
3.   Lower aliphatic amines are water-soluble. because they may establish hydrogen bonds with water molecules.The solubility of amines in water decreases as the molar mass of hydrophobic alkyl parts increases, Thus ,water does not dissolve higher amines.
4.   Amines are easily dissolved in organic solvents, such as ethanol, benzene, and ether. Intermolecular hydrogen bonds between alcohols and amines are stronger because of their higher polarity.
5.   The intermolecular interaction of primary and secondary amines is frequently facilitated by hydrogen bonding between the nitrogen and hydrogen of one molecule.
6.     With two hydrogen atoms present in the primary amines, the intermolecular interaction is stronger than secondary amines.
7.   There is no intermolecular interaction in tertiary amines because there is no free hydrogen atom to link with.
8.     At normal temperature, primary amines with three or four carbon atoms are liquids, while higher amines are solids.
9.   The arylamines, including aniline, are all colourless. However, if left exposed to the air, they will get discoloured owing to atmospheric oxidation.

Solubility

1.     Hydrogen bonds can be formed between water molecules and lower aliphatic amines. Because of this, amines such as these can be dissolved in water.
2.   The molar mass of amines increases when the hydrophobic alkyl portion increases. As a result, these amines are less water-soluble.
3.     Alcohols have a higher polarity than amines, making them more soluble in organic solvents, including ether, alcohol, and benzene.

Boiling Points

1.     Because of hydrogen bonding between nitrogen and hydrogen, primary and secondary amines participate in intermolecular interaction.
2.   Because primary amines have two hydrogen atoms for bond formation, they are more likely to form intermolecular associations than secondary amines.
3.   Because they lack hydrogen atoms, tertiary amines are unable to create intermolecular hydrogen bonds.

Analogs of Nucleic Acids

Biological proteins contain amino acids as a component. Amines are chemicals produced from ammonia and are involved in the synthesis of amino acids. Organometallic compounds having functional groups or nitrogen compounds with lone pairs of electrons, such as amines, fall under this category. Amino acids are the building blocks of many vitamins. One of the brain’s most important neurotransmitters, serotonin, is an essential amine. An important family of chemical substances, amines, can be found in a wide variety of plant and animal products, such as proteins and vitamins.At room temperature, amines can be liquids, solids, or gases. In many ways, amine research is enticing. In biology, the chemistry of amino acids is critical to understand the physiology  and pathophysiology of various occurrences in the human body. It’s a necessity for everything that’s alive. 

Conclusion

Organic compounds derived from ammonia are known as amines (NH3). Alkyl or aryl groups can be substituted for one or more hydrogen atoms to produce amines. There is just one pair of electrons in an amine, which is made up of a nitrogen atom. Ammonia can be converted into amines by adding substituent groups such as alkyl or aryl to one or more hydrogen atoms.

Some of the most important amine structures are amino acids, trimethyl amines, biogenic amines, and anilines. Although structurally they are similar to ammonia, amines have additional capabilities that depend on their carbon connectivity.