Multicycle Testing of P‐Mo–V Heteropoly Acid Catalysts in Oxidation of Substituted Phenols

Abstract

A series of valuable para‐quinones, such as 2,3‐ and 2,6‐dimethyl‐1,4‐benzoquinones (Me2BQs), were synthesized via oxidation of the corresponding 2,3‐ and 2,6‐dimethylphenols by using homogeneous high‐vanadium solutions of heteropoly acids: H11P3Mo18V8’O87 (HPA‐8’) and H17P3Mo16V10’O89 (HPA‐10’). These catalysts were shown to be capable of interdependent and reversible change of their acid and oxidative properties, the efficient regeneration of which can be performed for 25 min. The complete optimization of reaction conditions allowed one to reach the selectivity of the desired Me2BQs in 95–97% and shorten the oxidation time. The structural integrity of heteropoly anions present in the catalyst solutions was found to persist during the repeated performing substrate oxidation and catalyst regeneration. The catalysts showed the preservation of stability and efficiency for 25 cycles, demonstrating the prospectivity of high‐vanadium heteropoly acids in oxidation of organic substances.

Highly Efficient Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Furandicarboxylic Acid with Heteropoly Acids and Ionic Liquids

“…As reported for the conversion of cellulose to formic acid, introductionofv anadium into HPM could promote the selectivity,a nd then it would mainly be Vt hat favored the oxidation. [25] In addition, on the basis that HPMV n with more than three Vatoms is especially easy to reoxidize, [26] the oxidation rate was expectedt ob es ignificantly improved. HPMV n catalyzed the reaction mostly by the change of V V to V IV .…”

Catalytic Applications of Vanadium: A Mechanistic Perspective

“…References for manuscripts of homogeneous vanadium catalysis published in 2018 after the preparation of this document, but prior to publishing, which were not discussed in the text. − …”