Aromaticity - Aromatic Compounds


Aromaticity Definition

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.

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. 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 the special kind of stability.

Aromatic compounds

Aromatic compound 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 an 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 kind of aromatic amino acids called the histidine, tryptophan, phenylalanine, and the tyrosine serve as the 20 basic type 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.

Practise This Question

Calculate the rms speed of nitrogen at STP (pressure = 1 atm and temperature = 0C). The density of nitrogen in these conditions is 1.25 kg m3.