Reuse of a recovered, spent hydroprocessing catalyst in Indole acylations using cyclic anhydrides

Spent, wasted hydroprocessing catalysts from a petrochemical refinery were recovered from a consecutive draining-solvent extraction–calcination strategy. The activity of these recovered heterogeneous catalysts was evaluated in the acid-mediated indole acylation process. Thus, Bis-(indol-3-yl)-alkane diones were obtained when indole was reacted with cyclic anhydrides in presence of DMF as solvent and catalytic amounts of a spent hydroprocessing catalyst waste. In contrast, reaction between indole and phthalic anhydride afforded phthalimide in as major ptoduct