Aqueous Solutions of Mo-V-Phosphoric Heteropoly Acids as Bifunctional Catalysts for Preparation of 9,10-Anthraquinone and Its Hydrogenated Derivatives
, E-ISSN: 1867-3899
||Cycloaddition, Homogeneous catalysis, Molybdenum, Quinones, Vanadium
Zhizhina Elena G.
Odyakov Viktor F.
Department of Catalytic Processes of Fine Organic Synthesis
Boreskov Institute of Catalysis
Siberian Branch of Russian Academy of Sciences
Prospekt Akademika Lavrentieva 5, Novosibirsk 630090 (Russia)
Acid-catalyzed condensation of 1,3-butadiene with para-quinones and oxidation of resulting adducts can be performed as an one-pot process in the presence of aqueous solutions of Мо-V-P heteropoly acids (HPA) having the general HaPzMoyVxOb composition. The solutions have bifunctional catalytic properties, i.e. they are strong Brönsted acids and reversible oxidants. By condensation of hydroquinone, 1,4-benzoquinone, or 1,4-naphthoquinone with 1,3-butadiene in the HPA solutions, 9,10-anthraquinone (AQ) is prepared in the mixture with tetrahydro-AQ (THA) and dihydro-AQ (DHA). In the course of this one-pot process proceeding without organic solvents, the HPA solution is reduced. A slight soluble mixture of THA, DHA, and AQ almost quantitatively is precipitated and filtered off. The non-Keggin-type Н12P3Mo18V7O85 solution has the highest productivity in this process. This solution can be rapidly regenerated by dioxygen or air at temperatures up to 170С and then reused. The prepared (THA + DHA + AQ) mixture can be successfully used as a catalyst for alkaline delignification of wood. Our homogeneous bifunctional HPA catalyst is very stable and promising for use in similar one-pot processes.