What is the basic unit of all aromatic compounds?

The basic unit of all aromatic compounds is benzene. Benzene is a simple aromatic hydrocarbon with the molecular formula C6H6. Its structure consists of a six-carbon ring with alternating double bonds, which results in a stable configuration due to resonance. This unique structure allows benzene to act as a foundational building block for more complex aromatic compounds.

In terms of reactivity and properties, benzene displays characteristics typical of aromatic compounds, such as a distinct smell and a unique set of chemical behaviors, such as undergoing substitution reactions rather than addition reactions. This stability is one of the defining features of aromatic compounds, which distinguishes them from aliphatic hydrocarbons.

While other options represent compounds derived from or associated with benzene (e.g., phenol is a derivative with a hydroxyl group and toluene has a methyl group), these compounds possess additional functional groups or variations in the structure that differentiate them from the base aromatic unit, which is benzene itself. Thus, the understanding of benzene’s role as the fundamental unit of aromaticity is essential in organic chemistry and its applications in various chemical processes.