Low–Waste One–Pot Process for Obtaining Anthraquinone through Diene Synthesis in the Presence of the Solutions of Heteropolyacids
Chemistry for Sustainable Development
Boreskov Institute of Catalysis SB RAS
Acid catalytic condensation of 1,3-butadiene with para -quinones and the oxidation of resulting adducts can be performed in one technological stage in the presence of the aqueous solutions of Мо–V–P heteropolyacids (HPA) of general composition HaPzMoyVxOb. These solutions possess bifunctional catalytic properties being strong Brønsted acids and rather strong reversibly acting oxidizers at the same time. The condensation of 1,4-naphthoquinone with 1,3-butadiene in HPA solutions leads to obtaining 9,10-anthraquinone (AQ) in mixture with tetrahydroanthraquinone (THA) and dihydroanthraquinone (DHA). In the course of a single-stage process without organic solvents, the HPA solution is reduced and poorly soluble mixture of THA, DHA and AQ (up to 50 %) precipitates almost quantitatively from the solution. The yield and purity of AQ can be improved substantially due to the use of organic solvents miscible with water (for example, acetone, 1,4-dioxane), as well as high-vanadium HPA of the composition H15P4Mo18V7O89 and H17P3Mo16V10O89. Optimization of the process allowed us to obtain the product containing not less than 90 % AQ. Results achieved in the work open outlooks for the development of low-waste process for the production of AQ from 1,3-butadiene and 1,4-naphthoquinone.