Aromatic compounds burn with sooty flame because 

Aromatic compounds burn with a sooty flame primarily due to their high carbon content relative to hydrogen. The incomplete combustion of these compounds during burning results in the formation of fine carbon particles, which are released as soot. This phenomenon is more pronounced in aromatic compounds because their structure consists of stable, conjugated systems with a significant proportion of carbon atoms.

The sooty flame observed in aromatic compounds is a characteristic property that differentiates them from aliphatic hydrocarbons. When these compounds burn, the limited availability of oxygen in the flame zone cannot efficiently oxidize all the carbon atoms. Consequently, unburned carbon particles are emitted, creating a smoky and sooty flame.

Aromatic hydrocarbons such as benzene, toluene, and naphthalene are well-known for producing a sooty flame due to their high carbon-to-hydrogen ratio. This high ratio makes them more likely to undergo incomplete combustion, leading to the visible soot particles in the flame.

In summary, the production of a sooty flame by aromatic compounds is directly linked to their chemical structure and carbon-rich composition. Understanding this behavior is important in fields like combustion chemistry and environmental science, where soot emissions are of significant concern.