**1.1. Nitroaromatics**

Nitroaromatic compounds have at least one nitro group attached to the aromatic ring, like nitrobenzene, nitrotoluenes, nitrophenols, etc. In nature, nitroaromatic compounds are mostly found in natural products from different plants, fungi, and bacteria [5, 6]. The best known example of this is chloramphenicol, which is produced by *Streptomyces venezuelae* [7–9]. The role of some nitroaromatic compounds in cellular signaling has also been established. For example, 2-nitrophenol and 4-methyl-2-nitrophenol are well-known pheromones for ticks that enable them to aggregate and attach to mammals [5, 10] (Figure 1).

**Figure 1.** Nitroaromatics as cell signaling molecules.

In nature, several nitroaromatic compounds are produced by the incomplete combustion of fossil fuel, which releases hydrocarbons. These hydrocarbons produce nitroaromatic com‐ pounds after nitration with nitrogen dioxide present in the atmosphere. Mixtures of nitropolyaromatic hydrocarbons can be produced to form 3-nitrobiphenyl,1- and 2 nitronaphthalene,3-NT and nitrobenzene by a hydroxyl radical-initiated mechanism [11–15].
