Fabrication of activated carbon sulfuric acid as an excellent and novel solid acid catalyst, evaluating its catalytic activity in synthesizing 1,8-dioxo-octahydroxanthenes and 14-aryl-14H-dibenzo[a,j]xanthenes

Abstract

In this work, for the first time, a novel and innovative procedure has been utilized to chemically functionalize activated carbon (AC) based on the sulfonation reaction, which can be used in catalytic reactions as a strong solid acid. For this aim, AC must pass three steps of oxidation, reduction, and sulfonation, respectively. Therefore, the AC first was oxidized, then reduced by lithium aluminum hydride, and eventually participate in the sulfonation reaction with chlorosulfonic acid. We utilized diverse analytical techniques such as FT-IR, XRD, TGA, XPS, and neutralization titration to characterize and confirm our claim that activated carbon was functionalized. The analysis results indicate that sulfonic acid groups were successfully anchored with covalent bonds on the AC's surface. The resulting catalyst was used to synthesize 1,8-dioxo-octahydroxanthenes and 14-aryl-14H-dibenzo[a,j]xanthenes and showed good activity and stability in these reactions. Also, the produced products showed acceptable and good yields (87–97%). Reusability without loss of catalytic activity and simple fabrication method are other advantages of this catalyst.