Organic Chemistry: Concepts and Applications - Headley Allan D. 2020

Oxidation Reactions in Organic Chemistry
11.8 Oxidation of Aromatic Compounds

Aromatic compounds are cyclic compounds with a specific number of conjugated double bonds; these compounds will be covered in more detail in Chapter 17. Aromatic compounds are exceptionally stable and very resistant to many reaction conditions. In fact, some aromatic compounds such as benzene and toluene are used as solvents. In the presence of an oxidizing agent, they can be oxidized as shown in Reaction (11-90).

(11-90)

There are many important compounds in chemistry and biology in which the oxidized form of the quinone moiety is transformed into the reduced form. A classic example is that of coenzyme Q, also known as ubiquinone, structure shown below. Upon reduction, ubiquinone is transformed into the reduced form, ubiquinol as shown in Reaction (11-91).

(11-91)

Vitamin K₂ is another important aromatic system known as quinone, its structure is shown below, note carefully the oxidized quinone moiety.

Vitamin K₂ is essential for the synthesis of a blood-clotting agent prothrombin. A deficiency in Vitamin K₂ typically results in a fatal illness in which the blood is slow to clot. As a treatment for this problem, a modified form of Vitamin K₂, menadione, can be used. Menadione can be made from the oxidation of 2-methylnapthalene, as shown in Reaction (11-92).

(11-92)