Question

Which one of the following compounds is non-aromatic?

• A.
• B.

  

• C.
• D.

Answer 1

The correct option is B

Rules of aromaticity:

1. Cyclic molecule (a ring of atoms).
2. Planar molecular structure (all atoms in the molecule lie in the same plane).
3. The molecule has completed conjugation (p orbitals at every atom in the ring).
4. There are 4n+2 electrons in the molecule (n can be 0 or any positive integer).

The explanation for the correct options

(b)

• Organic compounds with one or more aromatic rings are referred to as "mono- and polycyclic aromatic hydrocarbons" or "aromatic compounds." Benzene serves as the parent member.
• Since one of the heteroatoms—oxygen, nitrogen, or sulfur—replaces at least one carbon atom in the CH group, heteroarenes are chemical compounds that have many similarities.
• These hydrocarbons with open and closed chains are referred to as aliphatic compounds. Only closed-chain compounds have an aromatic structure. They can be both saturated and unsaturated, and there are both open- and closed-chain systems.
• Aliphatic compounds are non-aromatic compounds that lack a ring structure, whereas alicyclic compounds, such as cyclohexane, have a ring structure.
• Aromatic hydrocarbons, like benzopyrene, frequently have several fused rings.
• Since this structure is not planar, hence this is non-aromatic in nature.
  Diagram:

The reason for the incorrect choices

(a)

• Aromatic compounds are any of a large class of unsaturated chemical compounds that have one or more planar rings.
• Because of their structure and mutagenic and carcinogenic properties, aromatic hydrocarbons are intriguing.
• The given compound satisfies all the conditions required to be aromatic, so this is aromatic in nature.
  Diagram:

(c)

• Any of a diverse group of unsaturated chemical compounds.
• An aromatic compound is any of a large class of unsaturated chemical compounds with one or more planar rings.
• Aromatic hydrocarbons are intriguing because of their structure and their mutagenic and carcinogenic properties.
• Aromatic hydrocarbons, like benzopyrene, frequently have several fused rings.
• The given compound satisfies all the conditions required to be aromatic, so this is aromatic in nature.
  Diagram:

(d)

• Aromatic compounds are organic substances that are mono- and polycyclic aromatic hydrocarbons.
• The parent compound is benzene. Aromatic hydrocarbons, like benzopyrene, frequently have several fused rings.
• The given compound satisfies all the conditions required to be aromatic, so this is aromatic in nature.
  Diagram:

The correct option is (c): A cyclic compound in which the overlaying ring does not have to be continuous.