Aromatic is a class of organic compounds that are distinguished by improved chemical stability. This occurs as a result of electron delocalisation within a ring system, which probably includes numerous conjugated binary bonds. The term refers to how these conjugated rings illustrate stabilisation in comparison to what would be expected from conjugation alone. August Wilhelm von Hofmann, a scientist, coined the term in 1885. Aromaticity is a characteristic of cyclic and planar molecules with resonance bonds that are more stable than connective or geometric structures within the same type of atoms in organic chemistry.
What are Aromatic Compounds?
Aromatic compounds are chemical compounds that are made up of conjugated planar ring systems with delocalised pi-electron clouds instead of individual alternating double and single bonds. Aromatic compounds are organic compounds containing conjugated planar ring systems with delocalised pi-electron clouds rather than discrete alternating single and double bonds. They are also referred to as aromatics or arenes. Toluene and benzene are two of the best examples.
Properties of Aromatic Compounds
The properties of aromatic compounds differ from other organic compounds. They exhibit properties following the delocalisation of pi-electrons present in the molecule. Some general properties of aromatic hydrocarbons have been listed below.
- These compounds are aromatic (additional stability granted by resonance).
- In these molecules, the carbon-to-hydrogen atom ratio is relatively high.
- When aromatic hydrocarbons are burned, they produce a yellow, sooty flame.
- Electrophilic substitutions and nucleophilic aromatic substitution reactions are the common reactions that are observed in these compounds.
- Aromatic compounds are generally nonpolar and non-miscible in water.
- These compounds are usually unreactive with few molecules and are used as solvents for various other nonpolar compounds.
- The carbon to hydrogen ratio in the compound is high; therefore, they are characterised by a sooty yellow flame.
Rule for Aromaticity
Huckel’s rule of aromaticity states that only planar, fully conjugated monocyclic polyenes have 4n + 2 π electrons, where n is an integer. That is, n = 0, 1, 2, 3, 4, etc., should possess aromatic stability. An aromatic compound must be planar and contain a cyclic cloud of π electrons below and above the plane of the molecule. It contains SP2 hybridised carbon atoms and must obey the Huckel rule. The aromatics compounds are said to exhibit some vital characteristics or called rules, that are listed below.
- The aromatic compounds possess cyclic structures.
- Each element of the ring within the structure must comprise a p-orbital ring, which is in a perpendicular form to the ring, and this makes it a planar molecule.
- All the compounds observed in Huckel’s Rule, i.e., all the aromatic compounds should have the (4n+2) Pi number of electrons.
Why is Aromaticity Important?
In the field of biochemistry and compounds present in living structures, the chemical reactions taking place are due to aromaticity. Listed below are a few cases that explain why aromaticity is important.
- The four kinds of aromatic amino acids present in the human body act as building blocks of proteins. These also help in building DNA and RNA among the molecules.
- The green pigment in plants is called chlorophyll, and it helps in photosynthesis due to the presence of aromaticity in its structure.
- In industries, the compounds such as styrene, aniline, phenol, polyester, nylon, and benzene diazonium chloride are all used in the production of various items such as bags, fabrics and cosmetics.
Applications of Aromatic Compounds
The aromatic compounds have their characteristics, and each compound is different from one another. Listed below are a few uses of aromatic compounds.
- Benzene is a widely used industrial chemical.
- Toluene is used in the paint industry in paint liquids such as thinners, glues, correction fluid etc.
- Benzene derivatives are used in cosmetics and skincare products.
- Most of the organic compounds are used in soaps and detergents, which act as cleansing agents.
- Medicinal chemistry takes a wide variety of aromatic compounds to test and produce new medicines as per requirement and also for research.
Aromatic compounds have their importance and recognition in all fields. As these compounds are irreplaceable and have a wide range of uses, it is used in all areas. Aromatic compounds have special and unique properties that one can research and innovate new compounds. Aromatic compounds and their applications are the vital creation of chemistry.
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