What is the Difference Between Polycyclic and Polynuclear Aromatic Hydrocarbons?

Polycyclic aromatic hydrocarbons (PAHs) and polynuclear aromatic hydrocarbons (PNAs) are terms used to describe the same class of organic compounds, which are often used interchangeably. These compounds are characterized by multiple aromatic rings, containing only carbon and hydrogen, and are produced by incomplete combustion or high-pressure processes. They are solids with low volatility at room temperature, have relatively high molecular weights, and are relatively insoluble in water.

Both PAHs and PNAs are composed of large organic molecules with multiple aromatic rings, and they have similar properties and characteristics. The term "polycyclic" refers to the presence of multiple rings, while "polynuclear" refers to the presence of many atoms. Some sources define PAHs as having multiple aromatic rings, precluding benzene from being considered a PAH, while others consider naphthalene to be the simplest PAH. In summary, the key difference between the two terms lies in their description, with "polycyclic" focusing on the multiple rings and "polynuclear" focusing on the many atoms. However, both terms refer to the same class of compounds.

Comparative Table: Polycyclic vs Polynuclear Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) and polynuclear aromatic hydrocarbons (PNAs) are both classes of organic compounds that consist of aromatic rings containing only carbon and hydrogen atoms. While the terms PAH and PNA are often used interchangeably, they have subtle differences in their definitions. Here is a table comparing the two classes of compounds:

In summary, PAHs consist of three or more fused benzene rings, while PNAs can have two or more fused aromatic rings. Both classes of compounds share similar production methods and occurrences, but their properties can vary depending on the specific structure and number of rings.