Alkyl-1,4-Benzoquinones - From Synthesis to Application

Alkyl-1,4-benzoquinones (ABQs) such as 2,3-, 2,5-and 2,6-di-methyl- and 2,6-di-tert-butyl-1,4-benzoquinones are versatile building blocks and also have many others applications known for this type of compounds. Nowadays the requirements of environmental safety necessitate revising preparation processes of such compounds and searching for alternative synthesis ways. Until recently, there have been many efforts to develop sustainable green processes. However, the efficiency of proposed methods differs significantly. For this reason, in this review we would like to outline a variety of chemical properties of ABQs in order to show their great potential as chemical precursors, to describe some interesting applications of ABQs and then to give description of existing ABQ synthesis procedures developed in the last few decades. The review summarizes advances in liquid-phase selective oxidation of alkylphenols with molecular oxygen, hydrogen peroxide, and t-butyl hydroperoxide by using both homogeneous and heterogeneous catalysts. Consideration of old methods for ABQ synthesis is of interest for understanding the evolution of preferences in the field and for comparing the efficiency of methods.