This document summarizes aromaticity in benzoid and non-benzoid compounds. It defines aromaticity as the property of conjugated cycloalkenes that enhances stability through delocalization of pi electrons. The rules of aromaticity are outlined, including that aromatic compounds must be cyclic, have planar p-orbitals, and follow Hückel's rule of 4n+2 pi electrons. Benzoid aromatics include benzene and polycyclic structures like naphthalene. Non-benzoid aromatics do not contain benzene rings and examples provided are azulene, tropone, and heterocyclic compounds.

1. Samrat Prithviraj Chauhan Government
College , Ajmer
Department of Chemistry
Aromaticity in Benzoid and non-benzoid
compounds
Submitted by : Manisha
M.Sc.[ Chemistry] Sem -I

2. CONTENT
• INTRODUCTION
• AROMATICITY
• RULES OF AROMATICITY
• AROMATICITY IN BENZENOID COMPOUNDS
• AROMATICITY IN NON-BENZEOID COMPOUNDS
• REFERENCE

3. INTRODUCTION
• Aromaticity is one of the crucial concepts in organic chemistry
because most of the organic compounds we come across are
aromatic. Organic compounds exhibiting delocalization of pi
electrons are aromatic and are referred to as aromatic
compounds. On the other hand, organic compounds which do
not exhibit delocalization of pi electrons are referred to as
non-aromatic or aliphatic compounds. Compared to aliphatic
compounds, aromatic compounds exhibit more excellent
stability.

4. AROMATICITY
• Aromaticity is defined as a property of the conjugated
cycloalkenes which enhances the stability of a molecule due to
the delocalization of electrons present in the π-π orbitals.
• 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.

5. RULES OF AROMATICITY
• The aromatics compounds are said to exhibit some 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
• The total number of π–electrons present in the ring should be
equal to (4n + 2), where n= 0, 1, 2 … etc. This is known as
Hackle's rule.

6. .
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.

7. AROMATICITY IN BENZENOIDCOMPOUND
• Benzenoid aromatic compounds are the organic molecular
species either with isolated benzene ring or with multiple
benzene rings which fused to form amore complex structure.
• Aromatic molecules are very stable ,and generally undergo
electophilic substitutions rather than addition . Since the most
common aromatic compound are derevatives of benzene.

8. . • For resonance diagrams the use of double headed arrow
indicates that two structures are not distinct entities but
merely hypothatical possibalities.
• These compounds further be classified into monocyclic
aromatic compounds and polycyclic aromatic compounds.
• MONOCYCLIC AROMATIC COMPOUNDS

9. P0LYCYCLICAROMATICCOMPOUNDS
naphthalene 111,1’-biphenyl
anthracene

10. Aromaticity in non-benzenoidcompounds
• Non-benzenoid compounds are the organic molecular species
either with all carbons in the cycle or with one or more hetro
atoms in the rings.
• A compound which exibhitics an aromatic behaviour but does
not contain any benzene nucleus.
• The non-bezenoid aromatic compound have one or more rings
fused but non of these rings is benzene ring . The ring might
contain 7,5 etc. number of carbons but that ring will not be
benzene ring.
• The most basic example of non-benzenoid aromatic
compounds is AZULENE . It is a system of two fused rings,
one containing 7 and the other containing 5 carbons.

11. .
Fig .- Azulene
• These compounds can further be classified into homocyclic
(carbocyclic) aromatic compounds and heterocyclic aromatic
compounds.

12. HOMOCYCLICAROMATICCOMPOUNDS
TROPONE TROPOLONE

13. HETEROCYCLICAROMATICCOMPOUNDS

14. REFERENCE
• https://www.masterorganicchemistry.com
• https://mltcollege.org
• https://www.britannica.com
• https://chem.libretexts.org
• https://courses.lumenlearning.com

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