One-Pot Process to Produce Anthraquinone Derivatives: Prospective Wood Delignification Catalysts

Derivatives of 9,10-anthraquinone (AQ) are widely used chemicals but the currently practiced methods for their production are inefficient and environmentally harmful. In the present work, an innovative method for synthesis of substituted AQ from hydroquinone (HQ) and substituted dienes (2,3-dimethylbutadiene, DMB) was studied with the synthesis of 2,3,6,7-tetramethyl-9,10-AQ (TMAQ) as an example. A solution of high-vanadium heteropoly acid H17P3Mo16V10O89 (HPA-10) was used as the bifunctional (acid and oxidative) catalyst for the new one-pot process. The influence of a number of factors on the key process parameters was studied. An insoluble mixture of two products (80% TMAQ and 20% DHTMAQ—an underoxidized dihydroderivative of TMAQ) was synthesized in 24 h under the chosen conditions. The mixture can be used as an effective catalyst for wood delignification. The results obtained offer real possibilities for developing low-waste processes of substituted AQ synthesis from HQ and substituted 1,3-dienes in the presence of HPA-10 solutions. The catalysts are highly active, stable and effective.