5) Is it cyclic ? ✓ Conjugated double bonds ? ✓ Is it planar? × # of π electrons 8 # of lone pair of
Q: Classify the following compounds as aromatic, anti-aromatic or non-aromatic – 1) Is it cyclic ? ✓ Conjugated double bonds ? ✓ Is it planar?
“There is no exception to the rule, that every rule has an exception.”- James Thurber. After learning all about aromaticity and antiaromaticity, we now proceed
Let us now begin to discuss the magnetic properties of aromatic compounds. 3]Magnetic properties. I) Aromatic ring current– Aromatic compounds have delocalised , closed loop
We have studied aromaticity in detail and are acquainted with various compounds that are aromatic. A variety of physical properties have been used as a
We have been reiterating that aromatic compounds have 4n+2π electrons and antiaromatic compounds 4n π electrons. Ever wondered why these numbers are so important? Let’s
We saw earlier that aromaticity refers to the extra stability that some cyclic compounds have, owing to their structure. Antiaromaticity means exactly the opposite of
Elemental carbon in its sp2 hybridized state can form some very interesting structures, which have very wide applications in industry. Fullerenes are one such class
Is annulene aromatic? annulene has 4n π electrons and so is anti-aromatic. It is highly unstable compound and exists only at very low temperatures. At
Annulenes are completed conjugated monocyclic non-benzenoid hydrocarbons, with a general formula – CnHn ,when n is an even number CnHn+1 , when n is an
In the last post we studied naphthalene molecule in detail and we understood why it shows aromatic stability. Similarly , other polycyclic hydrocarbons are also
In this post we shall discuss aromaticity of some polycyclic aromatic hydrocarbons (PAHs). What are polycyclic aromatic hydrocarbons? Poly = many cyclic = ring structure.
Furan, Pyrrole and Thiophene. All the above structures are similar to each other , except for the fact that pyrrole has a lone pair and
In the last post we studied some examples of homocyclic aromatic compounds. What happens if the ring has an atom other than carbon in it?
Benzene with six π electrons – the aromatic sextet– is a “perfect” example of an aromatic compound. In this post we shall study some examples
We learned in detail how HMO theory explains the structure and aromaticity of benzene in previous posts. In this post let us compare benzene to
Frost circles/Polygon method. This is a very useful mnemonic device for quickly setting down molecular diagrams for cyclic systems. Rules for drawing frost circles –
In the last post we saw how the HMO theory explains the aromaticity of benzene ring. In this post let us see how we get
In this post let us apply the HMO theory to see how and why benzene is aromatic i.e why does this molecule have that extra
In the last post we computed Hückel calculations for two p orbitals in conjugation. Let us now try to figure out how to calculate energies for
In the previous post we arrived at two simultaneous equations (We are using two different colors in order to distinguish between the two equations)- ciα
In this post let us apply the LCAO method and approximations we studied earlier to a simple conjugated molecule and carry out the calculations for
The HMO theory makes certain approximations.These approximations have proved to be very useful as they help simplify calculations and give accurate results. So, they are
In the last post we got an overview of what matrices are and how they are used. Let us proceed further and see how this
Before proceeding further, it is imperative that we understand some basic mathematical concepts required to study this theory. We are not going to elaborately study
Hückel’s molecular orbital(HMO) theory. The π- electron system in conjugated planar molecules can be treated independently of the σ framework. Aromaticity is usually described in
In the last post we introduced ourselves to a new concept in organic chemistry – Aromaticity. We will continue to discuss it in this post.
From this post onwards we begin discussing a new topic in organic chemistry.This topic deals with a certain class of organic compounds , which are
We studied the structure of benzene in the last post. However, the structure of benzene has many resonance contributors. The resonance structures of benzene
This topic is sort of a link between the earlier topic we discussed(Resonance) and the upcoming topic we shall start discussing soon. The structure of