Aromaticity - Aromaticity Rules

In the organic chemistry, Aromaticity describes the cyclic and planar molecules having resonance bonds exhibiting more stability than the connective or geometric arrangements within the same kind of atoms.


What is Aromaticity?

Aromaticity is defined as a property of the conjugated cycloalkenes which enhances the stabilization of a molecule due to its ability of electrons present in the ππ orbitals for the purpose of delocalization.

Aromatic molecules are said to be very stable and they do not break so easily and also reacts with other types of substances. The organic compounds which are not said to be aromatic are known as aliphatic compounds. These might be in cyclic form, but only the aromatic rings have a special kind of stability.

Aromaticity Examples

Aromaticity examples

Aromaticity Examples-
Benzene 3D ball structure

We encounter with Aromaticity in our daily lives, otherwise, our bodies would have never functioned in a proper way. Aromatic compounds are essential in the industry; and around 35 million tonnes of these compounds are known to be produced worldwide every year in the form of polymers and chemicals, such as the nylon and polyester. These compounds are important even in the field of the biochemistry of all the living things.

Most of the aromatic compounds are said to be the derivatives of benzene. The word “aromatic” in the real sense refers to the benzene derivatives, and as it was defined the way first. Also, there are many non-benzene kinds of aromatic compounds existing too. In the living organisms, take, for example, the very common type of aromatic ring is the DNA and RNA bases with double chains. The functional group of an aromatic compound or the substituent of it is known as an aryl group.

Aromaticity Rules

Aromatic compounds are less stable compounds and they have many kinds of chemical as well as synthetic uses. In fact, the nucleic acids and the amino acids that make up our cell structure make use of these aromatic compounds. But, the main thing is what makes aromatic compounds? The aromatics compounds are said to exhibit some of the special characteristics or called as rules which are given below-

  • The aromatic compounds are always cyclic structures.
  • Each element of the ring within the structure must and should have a p-orbital ring which is in a perpendicular form to the ring, and this makes it a planar molecule
  • All the compounds obey the Huckel’s Rule, i.e all the aromatic compounds should have the (4n+2) Pi number of electrons.
  • The last one is that the organic compound has to be flat.

Aromaticity Importance

Aromaticity plays a major role in the field of biochemistry of all the living structures. The four kinds of aromatic amino acids called the histidine, tryptophan, phenylalanine, and the tyrosine serve as the 20 basic types of building-blocks of the proteins. Also, the 5 kinds of nucleotides naming adenine, cytosine, thymine, guanine, uracil make up the main sequence within the genetic code present in the DNA and also RNA and these are said to be aromatic purines and pyrimidines.

The green pigment in plants called Chlorophyll has a kind of aromatic system. These compounds are also important in the field of industry. The most of the key aromatic hydrocarbons which are of commercial interest are the benzene, ortho-xylene, toluene, para-xylene. The hydrocarbons are produced from the complex mixtures which are obtained by the process of refining or distillation, and in-turn is utilized in the production of various kinds of chemicals such as styrene, aniline, phenol, polyester, nylon.

Frequently Asked Questions on Aromaticity

What are the four conditions for aromaticity ?

It should be in a ring form.
It should be planar or flat.
Every atom of the ring must be orthogonal to the plane of ring.
It must satisfy the 4n + 2 rule.

What do you mean by the term aromaticity?

This term is used to describe a planar, cyclic molecule with a ring of resonance bonds which is more stable when compared to other connective or geometric arrangements consisting of the same set of atoms.

what is Huckel rule of aromaticity ?

A molecule should have a certain number of lone pair of electrons within p orbitals or electrons with pi bonds within a closed loop of adjacent, parallel p orbitals in order to become aromatic.

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