Metal‐ and Acid‐Free Photocatalytic Approach Using Quinone‐Based Hyper‐Crosslinked Porous Catalysts for the Valorization of Glycerol into Solketal

Abstract

Two metal‐ and acid‐free anthracene (AN) and anthraquinone (AQ)‐based photocatalysts (HCP‐AQ‐2Ph and HCP‐AN‐2Ph) are synthesized and used for the effective acetalization of glycerol to obtain selectively solketal, an added‐value compound with several industrial applications and high demand as an oxygenated additive of fuels. HCP‐AQ‐2Ph and HCP‐AN‐2Ph are prepared by a Friedel–Crafts coupling reaction between the AQ or AN and biphenyl (2Ph) as comonomer which leads to the formation of high thermally stable hyper‐crosslinked porous networks with specific surface areas of 295 and 596 m2 g−1, respectively. Initial tests suggest that HCP‐AN‐2Ph is a less efficient catalyst compared to HCP‐AQ‐2Ph. However, subsequent runs indicate that during the first trial, the AN units are oxidized, resulting in a catalyst (HCP‐AN(OX)‐2Ph) just as effective as the AQ‐based one. The quantitative and selective conversion of glycerol into solketal is achieved in just 3 h using a 4 wt% catalyst and maintaining this catalytic performance for at least 5 cycles. In addition, the process can be scaled allowing the obtaining of solketal with high purity on a gram scale. These results place these catalysts among the most effective for the selective production of solketal from glycerol compared to previously reported metal‐ or acid‐catalyzed reaction.