Introduction of Aromaticity
The word aroma is used to signify the fragrance or the smell of an object. It has been observed that most of the aromatic compounds are derivates of benzene and even benzene has an aroma of its own, so these classes of compounds have been denoted as Aromatic compounds. Aromaticity has been usually used to refer to molecules that have resonance in them. Like in the field of organic chemistry, the term Aromaticity is used to describe the property of a cyclic, planar molecule with a ring of resonance bonds that exhibits greater stability than other geometric or connective arrangements with the same set of atoms
Some of the examples of aromatic compounds are Benzene, Naphthalene, etc.
Rules of Aromaticity
For a compound to be aromatic, it must possess the following characteristics such as:
The molecule must be cyclic, for example, Benzene.
Each atom in the cyclic ring must be conjugated. As it will facilitate the dispersion of the cyclic ring delocalized pi-electron system. Hence, we can say that every atom in the cyclic ring must have an empty p orbital and must be capable of participating in resonance.
All compounds that are aromatic must always obey Huckel’s Rule i.e. molecules must have 4n+24n+2 pi-electrons. Forex, Benzene has 6 pi-electrons and [(4×1)+2] = 6, thus it obeys Huckel’s Rule while cyclooctatetraene has 8 pi-electrons 4n+24n+2 ≠ 8, hence it does not follow Huckel’s Rule. So, benzene is aromatic while cyclooctatetraene is a non-aromatic compound.
The molecule must be planar or flat. Those compounds that follow the above rules of Aromaticity are generally flat as in that condition they possess extremely large potential energy.
FAQs on Aromaticity
1. What is Benzene?
Benzene is one of the most important compounds in organic chemistry. It consists of 6 Carbon and 12 Hydrogen atoms. Benzene was the first molecule in which resonance was observed and it has become very important from the perspective of organic chemistry. Every Carbon atom is bonded to two carbons and two hydrogen atoms. Benzene is a cyclical molecule and it is also planar as all the atoms of carbon are under the sp3 configuration.
2. What are the properties of aromatic compounds?
Aromaticity is one of the most important principles in organic chemistry, the organic compounds which have an aroma in them were found to possess special characteristics which could not be explained by the structure of their atoms alone. Some of the properties of aromatic compounds are:
The Aromatic compounds have extremely large resonance energy
The Aromatic compounds undergo substitution reactions rather than addition reactions.
These aromatic compounds have delocalized pi-electrons.
3. Why is it necessary for a compound to be planar in order for it to be aromatic?
The benzene molecule has 6 carbon atoms, all the 6 carbon atoms are in the sp3 hybridization, so in essence, we can see that all the 6 carbon atoms are in the same plane. When the carbon atoms come in a plane then there is an overlap of the p orbital inference region and the resonance of electrons start. So it is extremely important that the aromatic compound is planar so that there is a possibility for the p orbitals to share their electrons among themselves and gain stability.
4. Write about a non-organic aromatic substance?
Aromaticity as a property has been exclusively attached with organic compounds and their property of resonating among the atoms inside the compound so that the compound can achieve massive resonance energy which provides it stability. But there are also examples of aromatic compounds which are not organic in nature like Furan, which is a non-benzene aromatic compound. There are several examples of aromatic compounds. The Double ringed bases in RNA and DNA are also aromatic compounds.
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