One-pot process for preparing substituted anthraquinones via diene synthesis in the presence of solutions of Mo-V-P heteropoly acids

Abstract

The acid catalyzed condensation of substituted 1,3-butadienes with para-quinones and the oxidation of the resulting adducts can be conducted as one operation using aqueous solutions of Mo-V-P heteropoly acids (HPAs) of the general composition HaPzMoyVxOb. Being strong Bronsted acids and at the same time reverse oxidizers, these solutions have bifunctional catalytic properties. The condensation of 1,4-naphthoquinone (NQ) with 1,3-butadiene in solutions of high-vanadium HPAs with the molecular formulas H15P4Mo18V7O89 and H17P3Mo16V10O89 using a water-miscible organic solvents (acetone and 1,4-dioxane) gives 9,10-anthraquinone (AQ) with yields of 70% and purities of up to 97% upon the complete conversion of NQ. The reaction between NQ and substituted 1,3-butadienes under similar conditions allows us to obtain substituted anthraquinones with yields of up to 90% and purities of up to 99%. The catalysts are regenerated with oxygen in a separate stage and used multiple times.