Question

For the structure below, determine the number of pi electrons that count towards determining aromaticity. Indicate whether it is aromatic, nonaromatic, or antiaromatic. Number of pi electrons

Answer 1

Concepts and reason

Aromaticity: Aromaticity is the electron delocalization, which adds special stability to the molecule; using the number of electron count in the molecule, we can determine the aromaticity of the molecule.

Aromaticity of the molecule can be found by using the following rules:

1.Compound must be cyclic

2.Compound should have conjugated double bonds

3.Compound should obey Huckel’s rule

4.Compound should be planer

Fundamentals

In organic chemistry, to recognize whether any system (molecule/compounds) is aromatic or not, it will be identified using the term aromaticity. The aromaticity is extra stability provided to a molecule upon possessing the four criteria mentioned below:

1. Cyclic: Linear, acyclic systems are not aromatic and all the atoms in the ring must be involved in the (pi) system.

2. Conjugated: Every atom in the ring must have a p orbital. Therefore, the atom must be or, and every atom in the ring must be able to participate in resonance; not all the cyclic conjugated molecules are aromatic.

3. Huckel rule: The system should obey the electrons’ rule in the cyclic conjugated system. This is not the formula, but is used to identify the molecule as aromatic. Also, it tells us what the magic series is.If our pi electron value matches with the magic series, it is assumed that the system has the capacity to be aromatic.

4. Planar: If the ring is planar, there exists a good interaction between the adjacent orbitals.

Generally, if the first three criteria are met, then it’s safe to assume the molecule is planar.

The number of pi electrons is found as shown below.

Therefore, the total number of pi electrons for the given compound is ten.

The classification of compound can be done as shown below.

The given molecule is cyclic and conjugated. Therefore, it is an aromatic compound.

Ans:

The total number of pi electrons present in the given compound is.