Question

Cyclobutadiene is said to be:

• A. Aromatic
• B. Aliphatic
• C. Anti-aromatic
• D. None of the above

Answer 1

The correct option is C Anti-aromatic

According to Huckel's rule, if a cyclic, planar molecule has (4n + 2) $\pi$ electrons, it is considered to be aromatic.

Aliphatic compounds are chemical compounds belonging to the organic class in which the atoms are not linked together to form a ring. They are non-aromatic compounds.

Antiaromaticity is a characteristic of a cyclic molecule with a $\pi$-electron system that has higher energy due to the presence of $4n\pi$~electrons in it.

Unlike aromatic compounds, which follow Huckel's rule [(4n + 2) $\pi$-electrons] and are highly stable, antiaromatic compounds are highly unstable and highly reactive.

So, cyclobutadiene is an anti-aromatic compound as it is a cyclic and planar molecule having $4\pi$-electrons.